223 vs 556 - The Hidden Truth No One Tells You!

In this video we look at the real life measured differences between 223 and 556. I cover velocity, pressure, differences in brass, and much more!
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[@forgyde]

The correct answer is..... they BOTH fit in my AR. No problem.

[@samuelcolt6670]

With all due respect, fitting and firing charge strength is a bit different.

[@igoranisimov6549]

@@samuelcolt6670 get 223 Wylde chamber, it's a hybrid

[@igoranisimov6549]

@Itachirevived technically 5.56 chamber can use .223 ammo. And yes, I don't even use .223 barrels to avoid any issues. I develop my loads, which I personally call "223 remington". It only matters how much powder I put and what bullets I insert. Twist rate is another story.

[@macgyver5108]

@Itachirevived maybe you didn't make it to the end of the video? Pause and read at 10:59 closer. Using 556 ammo in a regular "223" marked barrel causes higher chamber pressure and possible sudden facial tissue loss... A "223 Wylde" marked barrel has a "hybrid CHAMBER" to safely shoot both 556 and 223, and usually does so more accurately too... BTW a 223 Wylde is not a barrel profile either, profile is the OUTSIDE shape of the barrel.

[@macgyver5108]

@Itachirevived your earlier comment! ".223 wylde is the only barrel profile I know of that allows both, but you should be careful firing 5.56 in a .223 non wylde"

[@pandemicprecision4603]

Came for science, got science. Got way more data than anybody else puts out. Bravo good scientist of the reloading world!

[@jtmcfarland3512]

Yeah, you got science specifically relevant for his rifle. Probably not relevant for yours.

[@CrashRacknShoot]

​@@jtmcfarland3512*IT'S. A. REFERENCE!*

[@jimdunkle4823]

Great info! A guy a work argued about 6mm and 243. He said he could load his 6mm hotter than my 243. I told him if my 243 with my load didn't do the job, I would use my 30-06!!! Why load any gun hot, it's just hard on the gun. Thanks for the video!!!

[@raam1666]

IDK, ask the Navy.

[@tubularfrog]

Having worked in laboratories for most of my adult life (retired now), your lab and your analysis are very impressive. Thanks for your video.

[@blainclatworthy5423]

I'm in the same boat, retired from a career in Advanced Ceramics Research.

[@rickdeckard1075]

provide credentials please, otherwise this is just misinformation

[@jgunther3398]

now i can do my dissertation on 223 and 556 vs inertial confinement fusion lasers

[@rickdeckard1075]

@@jgunther3398 the abstract will read "they dont work"

[@CrashRacknShoot]

​@@rickdeckard1075tf you mean "misinformation"? It's all spelled out as plain as it could possibly be in the video. As to the op you responded to, a dude can't compliment work? What were you on about when you wrote this? If you have any contrary evidence, I'll bite. I'd *love* to hear it.

[@meseahunt]

as a 22yr retired military person who has shot hundreds of thousands of 556/223 rounds, I can tell you that we NEVER had an issue when using 223 rounds in a 556, not once!!! i use 223 62gr in my personal 556 all the time with NO issues.... thanks for the video!!

[@seikibrian8641]

Yep. The rule of thumb is that you can always shoot .223 ammo in a 5.56 chamber, but not necessarily the reverse.

[@yfelwulf]

If you have a rifle in. 223 it needs the MILITARY THROAT which is longer than the standard 223 throat it was done to account for the fact military ammo may occasionally have a bullet not seated full depth this prevents the bullet jamming in the rifle when loaded causing an over pressure situation. My Ruger has the military throat I discovered this when I realised I could seat bullets beyond spec depth Ruger confirmed it had the military throat. THAT'S THE ONLY DIFFERENCE unless you need tighter rifling for different bullet weights.

[@brianjohnson6053]

@@yfelwulf i run a rock river with the wylde it will eat anything. Its so old it was when rra was buying barrels from wilson

[@tomacton6718]

it was Wilson Arms. W. Combat is a different company.

[@seikibrian8641]

@@yfelwulf "If you have a rifle in. 223 it needs the MILITARY THROAT which is longer than the standard 223 throat" The military doesn't use .223 Remington, it uses 5.56mm NATO. And if you're using .223 ammo, why would a "standard .223 throat" not work? As for Ruger, their AR platform is called the Ruger 556 for a reason. It's not called the Ruger 223.

[@skeetersaurus6249]

As a retired Marine, and reloader, I can say that 'I've acquired' thousands of empty LC brass (among several AAP's)...and I caught the differences almost-immediately between .223 and 5.56 brass. All else being equal (primers, powder and projectile), the brass (most-definitely pre-2004...which is what most of mine is) is THICKER! I first caught it, when I was loading 'rod' powder (IMR) and found that to reach 'upper load limits' (Speer reloading), I was having to PACK IT (compressed loads) to fit the charge in there...where with Win or Fed brass, it was a non-compressed charge. I mic'd a few cases, then ended up dremmeling a case in half, just to get some micrometer readings. I went to my older reloading manuals, and where .223 was seperate from 5.56 in loading data, I found that the case drawings were different as well (referencing that 'long case' situation...it only gets worse once you reform the brass in your reloading dies). By my own calculations, there is about 1.24 grains of capacity difference between .223 and 5.56 cases...and the thicker brass results in overall lower capacity (the 'extra brass' reduces the interior dimension). When you're loading with the 'default powder' for the 5.56 (Hotshot powder), this isn't an issue, though. Also, though you don't always see it, there is a varnish sealant placed on the primer (OEM Products), to make the cartridge 'waterproof' and 'humidity-proof', for long storage or damp environment use. It is usually a 'dark pink' in color. If you see that line circling your primer, then that is a sealed cartridge...something that I've never seen the .223 market do (adds cost to the product).

[@pb68slab18]

Word I always heard was that military/NATO 7.62 brass was thicker to hold up when linked for MG use. Always assumed the same held true for 5.56.

[@lurebenson7722]

AS you say packing powder into a 223 you will blow a gun up you liar and fake soldier. Powders all have different burn rates and the powders used for case size of 223 you don't do stupid reloading you fallow the reload data.

[@jacktheaviator4938]

I noticed the difference myself, and I look for the LC heavier brass. I am frankly jealous of your stash, lol. I am working on a 17 caliber wildcat I call "17 Fireball AI (Ackley Inspired)" using PO Ackley's formula of straight wall/40. So far it has shown a lot of promise for increased case life with hot loads

[@emmettpatterson3198]

I know this is a little late but in case you want to know I have sealed 223 with the "hot pink" circle around the primer. I think it was Igman ammo. Wanna say from brasil.

[@45-308]

I have noticed that different manufacturers have different wall thickness in the same cartridge. 30-06 remington case has different capacity then 30-06 Winchester brass.

[@iamcondescending]

I'd say for reloading: there's not enough difference to make a difference, as long as you load to what your rifle can handle/likes you'll be fine using both 5.56 and .223 brass. Just invest in a primer pocket reamer. As far as factory loads: I personally stick to the rule of "if it's labeled .223 on the gun: only use .223, if it's labeled 5.56: then you can use both."

[@winstongoodman3244]

Thats the rule of thumb I stick to In my AR15.

[@TreeTopFlier]

This is a very good video and very close to the answer. As stated, the 5.56 throat/freebore is longer than the 223. This is where the magic is. If you shoot 223 in a 5.56 chamber is will result in a lower pressure (as noted) and lower velocity, even though both cartridge's are intended to operate at nearly the same pressure. Moving the rifling out longer in the 5.56 has the effect of making the chamber larger without changing the case... a magnum trick. The pressure event, with rifle powder, happens when the projectile swages into the rifling and seals the combustion. Pushing the throat out in 5.56 requires more powder to maintain pressure. This extra powder will continue to burn as the bullet moves forward, ultimately producing more energy. In short, the difference is in the powder charge because of the different chamber. It is accurate to say the 5.56 is loaded to a higher potential not pressure. Finally because of the extra powder in the 5.56, loading it into a "true" 223 chamber will result in higher pressure. Probably near proof pressures.

[@carlossmith4927]

Best explanation yet. Thanks!

[@stevealford230]

Wylde stuff.

[@RatdogDRB]

THIS! This same explanation also applies to another fine AR15 based cartridge. The 6.8 SPC/6.8x43/6.8SPCII. The 6.8SPC=SAAMI spec. The 6.8x43 is equivalent to .223 Wylde in leade. The 6.8 SPCII is equivalent to to 5.56 NATO leade. In both, the SAAMI spec may tend to promote a slight higher accuracy potential, the largest chamber promotes reduced pressures, the middle chamber is the middle ground to try and get the best of both worlds. Where the 6.8 differs a bit is that the magazine for the AR15 is the limiting factor since it must fit inside the magwell of an AR15 lower. And, the timing of the gas operation vs. the pressure spike. A non-issue in a bolt action, where you have the option to load a bit longer to give a slight reduction in initial pressure, and the chamber remains sealed at the bolt until the shooter manually cycles the bolt. So, can a 5.56 round, loaded a little long be safe in a bolt action .223Remington? This would be what one should measure and determine for their needs. Another factor in secondary pressure from chamber to muzzle is the type of rifling used in the bore. A six-groove Enfield will apply more engraving force on the bullet, causing more drag/resistance/friction prior to the bullet clearing the muzzle. Both in even number (directly opposing forces on either side of the bullet) and the sharper edges of the rifling cut. A 5R or a 3R rifling will impart less engraving force, due to the softer edges of cut and offset engraving forces, allowing for a reduction in drag/resistance/friction. The bullet is free to move through the bore more quickly and helps in that secondary pressure.

[@zachsamay2026]

@@stevealford230 😂

[@ChadCooper03]

This is exactly what I was looking for. If everything is the same, including his chamber for testing, but getting more pressure and velocity from 556, then it HAS to have more powder charge. We’ll said?

[@50calprepper]

I’ve heard so many different explanations of the differences, that I just built all my rifles with 5.56 chambers and shoot whatever I have. No worries

[@dukecraig2402]

There is still one worry, you should never shoot soft point exposed lead bullets out of an auto loading rifle, the same holds true with shooting soft nose .30/06 out of an M1 or soft nose .308 Win out of an M14, when you do that you run the risk of a sliver of lead being shaved off of the tip while cycling the round into the chamber and getting lodged in between the casing neck and it's mating surface in the chamber, since all of those cartridges head space off of the casing neck this can cause issues that can lead to the weapon firing without the round being fully "in battery". Now you'll run into all kinds of people who'll say "That's a bunch of bull, I've been doing it for years...", well if anyone wants to second guess the SAAMI who are the people who do all the testing and research on firearms then God bless them, something like that may be rare but if you have my luck you'll get skin tore off your face the first time you try firing soft nose hunting rounds out of an auto loader. For shooting hunting rounds out of an auto loader safely is why Hornady developed the Ballistic Tip Polymer nose bullets, the plastic tip is the right material that won't have a sliver shave off and cause that problem.

[@chuckvan1568]

@@dukecraig2402 Wouldn't that be totally dependent on whether or not all the sharp edges have been removed from the feed ramps? And more of a concern during the break in of a new rifle? It seems right now the biggest concern is being able to source ammo while not paying the current extreme prices....

[@dukecraig2402]

@@chuckvan1568 Yes I'm sure feed ramp work would help but why not just run the polymer ballistic tip rounds? That's exactly what they're for and even though feed ramp work might cut the number of incidents from slivers of lead from soft points you have to assume that there's still going to be incidents of it happening so why take the chance of being one? I remember seeing reviews in American Rifleman and Guns and Ammo that showed them just as accurate as soft points of the same weight and the overall ballistics were the same. There's no advantage to running the soft points only a disadvantage

[@dukecraig2402]

@DrinkDaKoolaid What does looking down the barrel have to do with it? When that happens it happens to the round that's chambered not one before it, not that you can see the necked part of a chamber when looking down an M1 or M14. And you're exactly who I'm talking about when I said "You're gonna run into all kinds of people who say "I've been doing it for years..." that think they're smarter than the people at SAAMI". And hey, yea, I believe it's a free country, you can do whatever you want with your guns. I also believe in natural selection so hopefully the inevitable will happen BEFORE you reproduce.

[@dukecraig2402]

@DrinkDaKoolaid I'll have to get someone as stupid as you to translate that for me because it doesn't make any sense. "...don't have this giant conical piece of lead"? Wow that's truly some incoherent babble there.

[@jamesbarca7229]

A few years ago, I went through the same process (with the exception of the pressure/annealing) just to know for myself what the actual differences were. Your findings closely matched mine. Thanks for the validation.

[@tymz-r-achangin]

If you reload, just keep it simple by using the .223 reloading data for your 5.56 rounds For the past 5 years that I have been reloading my 223 and 5.56 with the common 55gn boat tail, I just reload all of them with the 223 recipe and I have absolutely no problems with any of the rounds whereby having tested these at 100 yards and consistently getting an average of 1 - 2 inch groups

[@buggsy5]

That is fine, if you are willing to settle for hunting accuracy. In any competition that allows reloads, you would end up at the bottom of the standings.

[@Scientist_Salarian]

@@buggsy5Sure, but 99.9% of shooters don’t compete. No solution is going to fit everyone.

[@arapahoetactical7749]

Great work! Extremely well organized and thought out.

[@guardianminifarm8005]

Appreciate all the thought, time energy & resources put into this information. Well done. Thank you.

[@3232jrob]

I have been reloading 556/223 mixed brass for many many years now with 55 grain FMJ and I can't tell any difference between the two.... same groupings at 100 out to 500 yd

[@robgoins3672]

A lot of factory .223 has the same velocity as .5.56 on the box mostly with Russian steel case. This was something I noticed a while ago. I always hand load at .223 pressures just to squeeze a little more life outta the case. I don’t actually know if it makes a difference.

[@Ramdodge582]

Same here.

[@gunndish]

Effin' aye Cotton!"

[@chrisallen3741]

556 has higher pressures and reset into the casing….

[@gunndish]

@@chrisallen3741 not my reloads ...

[@seaocean4868]

this is the quality video you only usually get from massive channels, well done!

[@kennethdahl4791]

Finally, someone who will tell the truth about 5.56 and .223. I have always said there is no difference between them, only the loading is different. This is the same as the difference between .38 ACP and.38 Super they are the same, only the loading and headstamp are different. What's more, have you ever heard of anyone having a gun blow up using the wrong ammo in a .223 or 5.56? I never have. Would any manufacturer of rifles ever take take that kind of liability on themselves making rifles in these calibers knowing that their product would be used with both kinds of ammo? Of course not. Ken

[@jordangouveia1863]

+1, that's why 357mag cases are 1/10" longer than 38specials so ya can't use the wrong ammo. This 223 v 5.56 is all BS it's good for lawn but that is all. I did read somewhere that some bolt action rifles with finely machined chambers in .223 may have head spacing issues with 5.56 ammo that could cause over pressure but that isn't the loading. Semi auto chambers are machined to a larger size than bolt action chambers for more reliable ammo feeding. The military ammo is in fact loaded down from a lot of commercial ammo to cut down on the wear and tear of rifles.

[@jimpeeden2004]

The same applies to 7.62 nato and 308 winchester, as a matter of fact not mentioned the original cartridge is almost always the civilian standard measurement before adoption to nato/military metric, and finally someone who doesn't deny that these cartridges use the same dies to reload each 5.56/223 7.62/308 etc...

[@ObservationofLimits]

The chamber is different is the main point.

[@0529mpb]

556 is simply 223 that follows a military spec like XM193 or M855A1.

[@ironDsteele]

I learned a huge amount from this video. It's especially helpful because I'll be starting to load some 5.56 from once fired mil stuff out of my gun. Thanks for the obvious time and effort you put in to this channel!

[@badvlad9861]

Crimp removal is a P.I.T.A., but only once.

[@theodorethompson9032]

@@badvlad9861 not with the right tools. Get the Dillon super swage remover. But I'd recommend just reloading 223. You can use the military once fired...

[@CrashRacknShoot]

​@@badvlad9861it's killer on the fingers after about 500 cases, but a reamer bit on the Lyman case prep xpress followed by a hornady primer pocket cleaner is the only way to go for me! The pockets come out cleaner pre wet tumble than the rest of the case does post tumble! 😄

[@JDude-uj3lk]

The information in this video is great and is greatly appreciated as a reference when discussing loads and differences between the two cases. Thank you for your time and effort in presenting such detailed info. I start my reloads at the middle of the reloading data and adjust from there. The only thing I've found that affects my loads are case manufacturer case capacity so I sort all my brass by that.

[@dtmelanson]

Love how you reference other good channels. Shows confidence in your work. And you should be. Great data, presented efficiently and well. Thank you.

[@whysoserious507]

Good comprehensive video. The major difference between .223 and 5.56 is this; The real difference is in the BCG and chamber. 5.56 chambers sacrifice some accuracy for higher tolerance, the military application, and double the ammo choice effectively, the civilian application. .223 guns on average have better accuracy but 5.56/ .223 will give you more flexibility in ammo. Now yes, you can in fact shoot 5.56 out of a .223 but I would not recommend it as your BCG/ chamber is not built for the pressure of 5.56 and you will have more wear and tear as a result until something inevitably breaks. The result may not be catastrophic and may take a while for problems to surface but it will eventually happen. Think of it as trading a 9mm for .40 barrel out of a pistol and shooting that. Your recoil spring and supporting features need to be swapped out as well as they were built for the tolerance of 9mm. It will be a slow burn of a failure. Hope this makes at least some sense, I’m tired and it’s early in the morning.

[@warpedweirdo]

Thanks for the data! I appreciate the effort you put in to generate it.

[@johnl.5117]

What a great piece of detailed work! Thanks for the effort and time to get to the true story.

[@markchapman2585]

I never shot a 223 or 556. That's why I like watching people that know what they are talking about. I only have old bolt action 30-06 from the 50s and old 12 gage from the 60s I got off my grandfather both gun's are in great shape for there age. Thanks for explaining 556-223 keep up the great work

[@leadxpoison9281]

I fired both 5.56 and .223 rounds out of my M16A2 in the Army in the late '80's. Apparently the military wasn't too worried about any difference.

[@helotaxi]

Because in the 5.56 chamber, the .223 load produces less pressure, so why would they be worried? The safety margin is higher.

[@ChickentNug]

If the M16 was rated for 5.56 (Which I think they always were), a lower-pressure cartridge should not be dangerous. Only concern I could think of would be if it could cycle the action properly with lower pressure, but .223 isn't low enough pressure for that to be a problem

[@Lex10999]

Awesome video. Thanks for taking the time to do the research necessary to give us this info. Really helps. Thanks again.

[@WardenWolf]

The safety issue was primarily from early guns that had been adapted from .222 Remington in the rush to bring the new cartridge to market. They used up their safety margins in the conversion, and companies weren't nearly as cautious way back then, so you had lightly-built break actions that were blowing up. Because everyone was well aware of the risks of someone putting 5.56 in a .223 chamber, generally speaking everything from the 1970's or later SHOULD have enough of a safety margin to handle it, and definitely since the 1980's. No one wanted that liability, so they put extra meat in their actions to handle it. That plus modern metallurgy has effectively eliminated the risk.

[@giles-df9yu]

The first ar tried by the army was loaded in 222 Remington. Remington owned the rights, so it was changed a little and called the 223. After the army tested it in 222

[@Will-dn9dq]

Still using ammo the weapons designed for is always the way to go. As my ccdw instructor Said you don't need to worry about bullet drop at 100 yards point center mass 1inch won't matter. So focus on what works don't be that guy w the exploding 50cal in ky.

[@phoenixrising4073]

@@Will-dn9dq that guy in KY didn't load that ammo. He bought it off someone else who loaded it wrong. It was supposed to be mil-spec and obviously wasn't.

[@Will-dn9dq]

@@phoenixrising4073 I know I watched it as it uploaded. Still putting steel tubes of nos in a shotgun is dangerous and dumb that lil sheet floppy Kevlar wouldn't do much u see the holes in it? 😆

[@phoenixrising4073]

@@Will-dn9dq You're talking about 2 different channels. The guy with NO containers out of a shotty is from CA and his channel is called toaflodermaus (or however you spell it.) The guy who almost died from the .50 exploding was Kentucky Ballistics and he doesn't shoot "junk loads" out of shotties. 2 different channels entirely.

[@ROOSTER333]

The best part if all this is the spinning object used to showcase the tools, freaking amazing

[@elrobo3568]

I am a 46 year police officer, 14 yrs in military. I was an armorer for my department and I have been reloading since 1970. I was in SWAT for 12 years and fired many rounds. I really appreciate your work and demonstrations. The bottom line in today's world is if I hit some bad guy at 120 feet with my 556 0r 223 he (or she or it or them----) will be equally dead. This discussion has been going on since I was issued an M-16 in 1966 and continues to today. there will still be those that think a 223 is a big 22 and a 556 is a cannon. I really enjoyed this! thanks.

[@Leonardokite]

Wow, as soon as you broke out all those instruments with the intention of using them to document the difference between 223 and 556, I knew this was not going to be any ordinary 223 versus 556 video. okay, now let me watch the video LOL And all I can say is...... excellent. You showed that the brass was basically the same, and that really the only difference is how close projectile is to the rifling which affects pressures somewhat. And when it comes to reloading, it is very rare that the hottest safe load is the most accurate. When shooting for accuracy pressures are generally lower and the accuracy sweet spot is at a point where the standard deviation of velocities of a group is the lowest. Of course making sure you get that right sweet spot means taking care of all other possible cartridge inconsistencies for the most uniform lot of cartridges possible.

[@sog4646]

I have a question 1 minute into this video. Did he say 18" sbr platform?

[@Leonardokite]

@@sog4646 what was the time stamp for that?

[@sog4646]

@@Leonardokite around 0:50

[@Leonardokite]

@@sog4646 oh, and I noticed you did say 1 minute in to the video. My bad. I guess I'm not quite awake yet hahaha

[@COIcultist]

I watched the film but missed, what were the digital calipers used to measure? Digital calipers are not a precision tool. If I were using them to measure repeat similar items, I might use them to compare each item to within 0.010" but generally they can't measure within 0.010" accuracy and if you are measuring to less than 0.002" you should slip gauge or use slip blocks to calibrate your micrometer and keep an eye on temperature.

[@FC-ef9dz]

Well done! Most stuff I load are plinking rounds at a mid range charge. Doesn't matter if I use 233 or 556 brass.

[@JollyThomas-jf9tf]

The 5.56 brass being thicker does allow 1 more Reload process without splitting the neck of the casing. I've been reloading 223 and 5.56 since 74 I've seen everything that could go wrong including over charge weapons explode etc etc etc the only reason we changed any load pressure was to perfect cyclic repetition and cyclic speed without missfire. The increase in fps was never a thought it was putting more lead downrange. Close quarters have need to be shorter for obvious reasons but when you put a 2" Barrell and 9" of flash suppressor on a full auto m-4 platform the gas tube length changes too and gas pressures are greatly affected so is cyclic timing and gas and flash build up at the muzzle can blind and burn the shooter. Larger gas tube and reduced pressure or a slower burn powder and lots of patience. Y'all keep in mind trimming your casing length properly each time you Reload will help prevent cyclic problems as well.

[@stonedog03]

Thanks for using actual measurements. That's so refreshing. Real data....I love it. Great video.

[@gungadinn]

6 of this, a half dozen of another. I cast every new barrel and chamber using Cerrosafe. Once cooled, it gets checked using a height gauge. The height gauge is verified against both .223 Remington and .556 go, no-go, and field gauges. Most of my casings are Lake City mil-surplus once fired brass, that get sorted based on weight. Test rounds loaded, then fired and case and primers examined. IMO, the load is safe provided the primers don't flat spot. This load can change (be reduced) with elevated temperatures. In my loading, 24.5 grains of RE15, is the maximum safe load when pushing a 69 grain Sierra Match King and a CCI #41 primer.

[@Williameagleblanket]

Baghdad, Iraq 2005. My brigade was deployed and we were on the zero range for our M-4’s. Loaded our magazines and started zeroing our weapons. Every single weapon was jamming up as soon we started shooting. Turns out, we were given UK 5.56 ammo. It’s not meant for US M-4’s. Had to collect all the ammunition and get the correct ammo for our weapons. Just another day in the giant sandbox.

[@puffnstuff12]

Bullpup can't take standard NATO pressure.

[@hotrodray6802]

THAT could be embarrassing in a fire fight. Once saw a 1911 guy stuff a 9mm mag into the 45. Plunk. Another embarrassment.

[@drizzintahl]

I love the way this video is done. It cuts straight to facts but also quickly goes over why it matters, or in a lot of cases, why it doesn't. Well done!

[@daviejones5317]

I work in the gun industry and this is something I have to explain at least once a week. Glad to see data to prove Ive been explaining this correctly. Thanks great vid man.

[@PikesPeakTacticalGunsmith]

Ton's of great information in this video. The biggest difference between 5.56 and .223 brass is the case wall thickness near the case head. 5.56 has a thicker case wall since its supposed to produce higher pressure. Also, a 5.56 chamber is rated to 60,000PSI whereas a .223 chamber is rated to 55,000PSI (Per SAAMI). Firing a .223 out of a 5.56 is generally acceptable since there is no reason the lower pressure round would cause issues. Firing a 5.56 from a .223 chamber could result in increased wear and possible damage to the system due to the higher pressure, but you'd have to be putting quite a few through it and rapid speeds to produce enough stress to cause a failure in the chamber.

[@jvalentine8376]

Nice work very interesting video . Having used the 5.56 Nato in the Military and been a .223 Remington shooter for last 50 years the results are about what I expected . The Military 5.56 round is loaded to a slightly higher pressure but not dangerous to fire in a modern strong proofed rifle . I have fired a lot of 5.56 in my 223 Howa bolt action and had no issues other than a few case neck splits which were most likely due to old military surplus ammo going a bit hard . When hand loading the natural variations that are inherent in different rifles in how they handle pressure is way more than the difference between 223 and 5.56 anyway . So you load either to suit your gun . I have heard of people with really tight spec 223 chambers saying they can't chamber some 5.56 ammo . Sometimes this is attributed to the rough manufacture of Military ammo that has a slight bulge on the shoulder face . Seen the same thing happen with some European 7.62 Nato ammo into a 308 Winchester chamber .

[@AaronBrand]

Thanks! I’ve been using “223” specs and dies for reloading 556 brass, which I find in the hundreds at my local range. Works great in my 5.56 chambered firearms.

[@brianjohnson6053]

Its more of the extra pressure between the 5.56 and the 223. Odds of it happening are small but im not willing to self destruct a fire arm because of wrong ammo

[@LuvBorderCollies]

@@brianjohnson6053 You won't even come close unless you do something very very wrong as in wrong powder as in a much faster burning powder.

[@timubels2430]

Great video. Very nice to see the work you all are doing. Keep up the good work. Thanks.

[@msromike123]

Holy moly. That's an impresive array of instrumentation!

[@grahamohea2424]

I can understand a rationale for loading to the headstamp (5.56 loadings in 5.56 brass and .223 loadings in .223 brass). If you are the only person who will ever use the ammo, then there is no reason to separate them, but if there is any chance that someone else may (borrow from you, share with friends at the range, etc), the correct headstamp can help to make sure that they don't put hotter ammo into a rifle that is not rated for it

[@chipsterb4946]

Damn good point I hadn’t thought of.

[@Joe_Brown99]

And we only bought firearms stamped 5.56 so we (can use) either

[@xephael3485]

LC just says LC because they probably wanted to put this stupidity to rest... and stamping LC is easier.

[@rjstewart]

If you are loading mixed 223/556 brass with 223 load data then it shouldn’t matter to anyone else who might use your “5.56” ammo in their “.223” gun.

[@detritus23]

@@xephael3485 Nothing to do with the question of 5.56 vs .223. LC produces brass for the military and sells the excess to civilian manufacturers. Rather than put a head stamp that would force the issue, they keep it generic. Also, for their application (i.e., military), there is only one loading going into the brass.

[@lobstersrs]

Excellent video, very thorough, lots of information here. Although it's honestly more information than I personally have use for, it's interesting none the less, and I appreciate the effort you went through in compiling and presenting it.

[@josephtutela1066]

The BEST analysis I've seen! and the answer is?? my mini-14 (series 180) manual says 5.56 AND .223! Thank-you for your excellent work...

[@michaelgriffith457]

Knowledge is important. We must be willing to learn new things and to question not only our own understanding but that of others. That is how we grow intellectually. Excellent video

[@OtisFlint]

You reload based on the chamber it's going in, not the head stamp. This can also apply to shoulder setback on resizing, depending on application.

[@sisleymichael]

Your advice at the end, practice safe reloading and start low and look for signs of pressure as you increase. Excellent advice. I found my most accurate load for 223 slightly over half way up the load range using TAC and a 55gr bullet. That load has resulted in more than a few DRT coyotes. Anyway, loved this video.

[@imeprezime1285]

"look for signs of pressure". Where/how?

[@titusflavius5668]

@@imeprezime1285 look for very flat or flattened fired primers first and also cracked case heads. Flat primers are the usual suspects. Be careful and use all PPE when reloading and shooting. If you aren't comfortable with reloading or shooting, get some professional training and instruction before attempting these activities.

[@cam_DA_Hawkdriver]

Loved the onscreen stats. That’s the way to present data in a video. Good job! Bottom line, I can fire .223 all day long in my chambered 5.56 (and I have, never had an issue).

[@user-vf3gf4xq3v]

Finally someone that knows what they’re talking about. I’ve listen to all the hype about the differences and I was perplexed at how they arrived at this given that the main difference is free bore chamber dimension. From a practical field use standpoint point no difference.

[@johnfarrar6715]

There is NO 5.56 that fires at over 29, 000 feet per second!

[@timothyrichburg7331]

Excellent analysis! Pure data and no subjective opinions. Thanks!

[@jacquesmaree2178]

As I was in the army here in South Africa we use to take sharp point amo in 308nato and use as it is in my 308 for target shooting practice. The same we did with the .223 and the so called 5.56nato difference they both fitted visa versa in a lot of different rifle manufactures without any problems.

[@johnryan9626]

Thank you much for all the time and thought put into this.

[@pandorasflame7742]

I run an LWRC M6 and Sons of Liberty Gun Works M4. Both recommend 5.56, but I run whatever I can afford. I also used to have a Smith & Wesson MP15 which recommend using .223 instead. Out of all 3 rifles, my groupings DID NOT change significantly between similarly loads of 5.56 and .223, and neither experienced any failures. I do still prefer 5.56 due to my rifles and suppressors typically being tested with M855. M193 is widely available and usually what I see discounted. That being said, I did just order 120rds of Norma .223 for testing recently and I'm eagerly awaiting its arrival so I can evaluate it for myself.

[@edjett2631]

I'm just an old retired mechanical engineer that has been shooting and reloading as long as I have been an engineer. I think the difference is primarily the pressure level. The chamber differences are primarily set up in the military rifles to improve or facilitate chambering in a battle situat.ion for feeding reliability. Also military ammo is expected to be fired and cases abandoned, not reloaded. All that said, I have only dealt with one .223 Rem rifle, but have not fired any 5.56 military ammo in it. Pressure matters; I prefer to shoot .223 ammo in all rifles I have access to. Even rifles marked 5.56.

[@kidsonblackops]

They actually do reload a decent amount of range brass in the army. We aren't required to recover each piece of brass by any means but there's a weight standard.

[@kidsonblackops]

For what it's worth I'm Jr. Enlisted so that could be a blatant lie to get us to clean well

[@GeorgiaBoy1961]

@ Ed Jett - What you say makes sense. Back in the 1950s and going forward, the NATO alliance set up standardized specifications for its small arms cartridges so that in theory any NATO soldier or unit could resupply anywhere inside the alliance and have ammunition which would perform to the expected standard. This was done in part to ease logistical challenges, but also to assure that M193 or M855 5.56x45mm NATO would withstand the firing cycle not only in rifles and carbines, but in base-of-fire fully-automatic weapons. Combat conditions mean that the ammo has to work not just when the weapon is clean, cool and well-lubricated - but when it may be hot, fouled, dirty and in need of lubrication during extended use in a firefight. Since combat accuracy and match-grade competition accuracy are not necessarily the same thing, many mil-spec weapons sacrifice a bit of accuracy and precision in the form of more generous chamber and throat dimensions, to aid in problem-free chambering, firing, extraction and ejection. NATO cases are said to be stiffer and stronger in the head area to avoid tearing during extraction. After this video, I wonder if they really are significantly stronger and stiffer than .223 brass? It seems plausible that ammunition companies would not retool separate lines for making 5.56 and .223 Remington brass, when it would be far-more-economical just to make the civilian brass to a similar standard or even the same standard as mil-spec stuff. The one thing this well-done video didn't do was delve into metallurgy. Annealing is somewhat of a surrogate for that, but not entirely. I wonder if a physio-chemical analysis was done using atomic absorption mass spectrometry and similar methods was done, what the results would reveal? But that's just my inner chemist coming out.

[@JamesWalker-ng1qh]

One other interesting thing to note when this conversation inevitably comes up, if you measure how the chamber was actually cut vs how it was labeled, it is not uncommon (especially on budge AR type barrels) to find that a 223 barrel is cut to 556 specs or vise versa. People who don't know, speak very strongly on this whole debate like 556 is loaded with red dot or something.

[@markhoffman2960]

Good work! I have learned so much from your work and the fine comments sent in.

[@jeffryblackmon4846]

More data than I can possibly use! Well done!

[@moushunter]

One of the best differences I've heard and would account for the pressure differences is that .223 Rem is factory loaded with small rifle primers while 5.56 NATO is loaded with magnum primers. In my reloading experience the difference between small rifle, small rifle magnum, and the CCI 41 for 5.56 NATO is only in the primer cup hardness. I don't notice any difference side by side in accuracy or velocity comparing those primer types in various brands. I do feel the difference between brands of brass when prepping cases. PPU and CBC brass seem a little harder than most other cases when trimming once fired brass to length. I've noticed FC cases seem to lose primer pocket integrity after 4 or so reload cycles where others last at least 8 cycles (annealing case mouths every 4 times). I do have LC and PPU brass that have been reloaded a dozen times or more. Some European imported .223 and 5.56 cases seem to have thinner case rims that routinely get damaged from extractors and can get pulled out of shell plates and case holders on reloading presses. Sort of off subject but I've been finding a lot of recent commercial 9mm cases with crimped primer pockets and some where the primers appear to be chemically sealed into the pockets. I've had a few hundred where the deprime pin actually poked through the spent primer without moving it from the pocket. That wreaks havoc on a progressive press.

[@ftn5546]

I just cull that brass. If you want to save that brass, add an extra decap only stage using a Lee universal decapping die; it's actually a very good Lee product.

[@t-bfr45-70]

556 is 223 with a larger then 60 grain bullet trying to hit a speed the military wanted the pressure ended up higher than they saami spec with a standard 223 chamber so they increased the throat to low pressure which in turn make it no longer able to be a saami 223.

[@harpintn]

When I was trying to decide between a .223 and a 5,56 I was told the difference was that 5.56 was loaded to higher pressures. I am glad that the work you did confirmed what I was told.

[@everettcalhoun8197]

My father was an artillery specialist staff sergeant during WW2 . Growing up he would explain the twist. (rifling), charge pressure as it relates to the projectile weight.. Years later I would run into hunters that shot my fathers reloads and they would tell me that his loads shot straighter than any other shells they ever fired.

[@harpintn]

@@everettcalhoun8197 I used to reload plinker .38 rounds for my .357. I am aware that many people were very good at tuning their rounds to their firearm. I never got that serous about it. I just liked to kill tin cans.

[@johnlong384]

Thanks for your very detailed reports and for the +/- 12 dozens of hours you have invested in the matter!

[@ottokiehl5413]

Excellent information. Thank you for doing that work.

[@MrHuntfishdive]

Great video as always. All I know is I have a 5.56 barrel but all my loads use 223 data no matter what case I’m using because that’s what I find the most data for.

[@BoltActionReloading]

There is very little data that is out there labeled as "5.56" (Hornady does, but very little overlap with the 223 bullet selection and where there is differences are ~.2 grains) I thought about detailing this but tried to leave the video as basic as I could. I am sure many that watch wont care about load data.

[@bobsullivan5714]

These comments are the best I have seen anywhere on KZbin! The rebuttals and challenges were done with the exchange of information not disrespect! THIS is the content that helps reloaders/shooters like me learn the stuff we should have known to begin with. Special thanks to Duke Craig AND those who challenged him. WELL DONE!

[@Bryan-yq9pz]

Finally, 98% of the answers I have been looking for in this comparison. Thank You

[@ryanupchurch9683]

I thought the 556 uses “harder” primer so in full auto use it’s less likely to detonate if it has a hammer follow strike? Just something I heard. I have no skin in the game. I don’t care. I have no ars just a 30 carbine for ranch work and a 6 lbs 308 bolt to hunt with. I’m old and they were free

[@NHGUIDE88]

LOL... You have a great way to explain this all but when you said 29"thousand"49 feet per second... then said similar things a little later...30thousand96 and 32thousand31 feet per second...I had to chuckle that, yes, everyone makes mistakes just like I do! I know * and we 'all' know what you meant*, but it did bring a smile to my face. Good video and explanation overall. I'll keep watching and no doubt learning, too.

[@jeremymcadam7400]

How else are you going to shoot Chinese satellites out of the sky?

[@scottboelke4391]

I treat the 2 exactly interchangibly. Thanx for basically saying the same.

[@markadams7597]

Very helpful information. Thanks for sharing this data. Very convincing.

[@Jetmech1781]

I've always heard it's all about pressure. .223 in 5.56 is fine, but never in reverse.

[@mmelgoza1983]

I follow Gavin's tip about loading 5.56 marked brass to 5.56 pressure and 223 to 223 pressure only because I never want to shoot a 5.56 load out of a 223 chamber. I have all three chamberings and I don't have a perfect memory. Easy to just look at what's marked on the case. Excellent video, as always!

[@kevinpratt7766]

Wow! Impressively thorough! Well done!

[@tonytsquared5576]

I am using once shot Lake City brass for reloading. I had a military source that gave me 3 five gallon buckets of it 20 years ago and I am less than half way through it. The military crimp is a bit of a chore to to get out but I am loading 62gr boatail projectiles to 3020fps. This load works well for my Mini-14 and my AR. I full case resize, trim, and anneal every third reload. I get 12 to 15 reloads before the neck splits. When the necks split I give those cases to my BIL to cut down for 300BLK cases. I keep about 2000 rounds in rotation but could easily double or triple that with my reloading supplies that I keep on hand. I shoot more handgun but I do range day once a month for rifle.

[@barnybrewman1571]

Excellent job in comparing the two rounds. Personally, I've put thousands of .556 rounds through my .223 rifles, without worries or problems, although I recommend you follow your manufacturers recommendations. However, the .223 proof loads are at a much higher pressure than your average 556 ammo, so catastrophic failure is not likely, even after multiple rounds.

[@brianjohnson6053]

Guess i will keep running what is stamped on the barrels worked for 40 years now

[@johnnash5118]

Excellent presentation, the only other variable not mentioned would be barrel/chamber metallurgy and their pressure limits, but I bet there isn’t any. Liked and subscribed.

[@hybridracers]

I've been lied to forever! Thank you for this information

[@BWALK551]

Great video ! My dad had a bolt gun chambered in .223. He called me on day saying there was something wrong with his rifle. He said everytime he shoots the plastic end cap of the bolt would come off and the primers were popping out of the cases and he could feel pressure on his face. Yep , he was shooting 556 ammo in his .223 chambered rifle.

[@bubblegump5410]

that happens with an air soft rifle

[@douglasphillips24]

I've shot both through my 5.56 no problems. Thanks for the knowledge.👍

[@CitizenSoldier500]

yep just not the other way around

[@fubarmofo6969]

@@CitizenSoldier500 it’s not gonna harm anything if u do… barrel will just wear out faster. Anal ppl make a big deal over tiniest things. All my mags have always been mixed .223&5.56 and have tens of thousands of rounds thru ars with zero issues

[@andreschondelmaier4834]

I'm a sucker for velocity so tend to build up my loads always looking at pressure signs . And seating depth depends on the shape of the projectile , by blueing projectile on an unprimed empty case and seating bit by bit until no witness marks are found from the rifling ( just off the rifling ) you need one of these for every type of different projectile. Use this dummy for setting up dies . I Also only neck size on brass fired from the rifle being loaded for . Chronograph as I build up the loads in 3 shot groups. As the velocity increases you will notice that groups will get tighter and then start getting bigger again and then tighter again This is due to barrel vibration and there may be several sweet velocities with good groups 😀 but usually one of these is better than the others that's where you fine tune the power load . This is the optimal velocity for any projectile for that barrel regardless of weight. So keep an eye on pressure signs as specially on heavier bullets . Always start of conservatively! At the end of the day who really cares if it's 223 or 556 ? When you reload you optimise it for your rifle . Happy accurate shooting to you all .

[@LRHutch]

Thanks for the video. Very informative. I knew most of this info already. I hope a lot of people who really don't know their ammo watch this video. I certainly will tell people to watch it.

[@williamodell8634]

Great Info Helps a lot for reloading this round

[@alanrobinson2901]

Ok, the issue I see here is the test barrel. The entire idea behind the Wylde chambering was to help negate the pressure issues when shooting 5.56 in a .223. Flat out, the pressure issues are when a 5.56 is fired in a shorter throat .223 chamber, so testing in a "go between" chamber like the Wylde took away MOST of the issue. This is why ALL my handbuilt AR's are Wylde chambered, it truly is the best of both worlds. As to the actual danger of shooting 5.56 in a .223, I sold guns for many years, and I sold a Ruger Ranch rifle to a fella who proceeded to shoot an entire case of XM 855 through it and ended up with a cracked receiver. WAY too much pressure for that gun. So I have personally seen the danger and damage done when not knowing the difference.

[@LuvBorderCollies]

My response is I seriously doubt that Ruger Mini guy only shot factory M855. There is a way to ramp up a normally very safe into the stratosphere. Get a POS Galil cobbled together by Century so the mags sat too low. This caused bullets to ram the barrel which set the bullet back. This will cause a dramatic overpressure with primer pockets enlarged to Large Rifle or at least that's how they looked. Got some stings on my right arm but glad it wasn't worse. No Century made junk no more. FWIW some of the bullets were pushed in so far only the tips could be seen at the case mouths. After 50 years of reloading centerfire rifle mostly 223 & .308 Win IMHEO the 223 is a sweetheart cartridge to reload and shoot. Its a forgiving round but you still have to pay attention to detail.

[@alanrobinson2901]

@@LuvBorderCollies Well, I know for a fact he shot only those Factory rounds, and I suspect he went to town on the gun, meaning that he fired as fast as he could with many mags, and I suspect the receiver just got hot as hell. Anyone who has ever shot the AC 556 (and I have, at Knobb creek) will tell you that gun heats up faster than many others, it was just built too light for auto or sustained fire.

[@LuvBorderCollies]

@@alanrobinson2901 I never abused any of the Mini 14's and the Mini 30 I had. Still got a G/B but I've never shot it. It looks neat and that's why I still have it. Totally believe the fast heat up. The Mini 14 was never designed to be a military weapon even if it resembles one. It certainly was not designed to be an accurate one either. Thanks for comment as I'd never thought of that angle. If you were on Patreon I'd buy you a coffee. 👍

[@immikeurnot]

I found the myth of 5.56 being higher pressure comes from .223 being rated by the SAAMI spec, but everybody was looking at the 5.56 spec which was in C.U.P. which is in no way comparable and can't be converted. The military now uses testing methods that fall in line with SAAMI, and their stated maximum average pressure is now also in line with SAAMI's specs for the .223 Remington. The American Eagle in particular is identical except for the head stamps between their 55 grain 5.56 or .223. Same bullet loaded to same OAL, same muzzle velocity from the same rifle.

[@t-bfr45-70]

When fire a NATO 556 in a tight chamber 223 you pressure can exceed the pressure of saami 223 in a 556 chamber it will nearly equal to a 223 in a 223 chamber from all the information I found. The biggest issues come from 223 was designed around 55gr and lighter bullets where 556 was 60+grain steel core bullets which are longer so contact lands sooner creating a little more pressure. As for some manufacturers they will label what is in truth 223 as 556 just for sales. But when it come to NATO spec 556 it not the best idea to shot in a tight 223 it on the chrono you can actually see speed difference.

[@bullboo1]

@@t-bfr45-70 Originally 5.56mm had the higher pressure regardless what system used and a throat .125 longer so using old pre 70s 5.56 in an old 223 rifle would cause 10,000 lbs more pressure in that rifle. Now the ammo has changed to suit both weapons.

[@t-bfr45-70]

@@bullboo1 what year did 5.56 come out? I don't think m855 has changed. Just the fact that company's label what is actually 223 as 5.56 to get the sale's. 223 is 5.56 but that is different then 5.56nato.

[@helotaxi]

The testing methods and allowable pressures could be identical, however the chambers those pressures are tested in and spec'd for are not. Spec loaded 5.56 NATO cartridges produce the allowed pressure in a 5.56 NATO spec chamber. The SAAMI spec .223 chamber has less freebore which means that for cartridges loaded to the same OAL/ogive datum, the bullet will engage the rifling sooner and with less velocity in the .223 chamber. That means a sharper spike in pressure and in the case of 5.56 NATO ammo in a .223 chamber, the pressure is going to be higher than the .223 ammo in that chamber and higher than the 5.56 ammo in a NATO spec chamber, thus exceeding the rated chamber pressure. In some of the tests that I've seen, exceeding it by a very significant margin.

[@t-bfr45-70]

@@helotaxi very well put

[@thelotec007]

Nicely done brother 👍 It's about time 😎

[@nigelcrete3901]

Well done. Good informational video. Very thorough

[@MitchFlint]

Your test is impressive, but neglected to physically compare the different chambers against each other. During a wildcat development, I noted that a difference of just 0.010 in freebore in the same barrel made a significant difference in pressure curves.

[@helotaxi]

@@DBeskar6605 The pressures in this video were all measured in the same .223 Wylde chambered barrel. The pressure differences measured here are the differences in the load, since the chamber is a control. A SAAMI .223 chamber has a steeper leade angle and shorter freebore than the Wylde chamber. The 5.56 NATO chamber has even more freebore than the Wylde but I don't remember off the top of my head the difference in leade angle. The Wylde chamber was designed specifically to allow both .223 and 5.56 to be safely fired without the potential loss in accuracy that the extra freebore of the 5.56 chamber can create. There are plenty of chamber pressure plots out there showing the different loadings in the different chambers. The pressure differences are much more significant in the .223 chamber with its reduced freebore and steeper leade.

[@FreedomFroggear]

This is fantastic! Thank you for the real info. I honestly didn't know much about the difference. I run both through my ARs and they seem to perform pretty similarly to me. It's great to know what I'm actually running through my rifles. I have been shooting for a long time but I'm a novice at best when it comes to loads.

[@ronvalentine-ml3hv]

Very nice stats , I appreciate you people getting right to the numbers . 🔱

[@gbtriumph3216]

THANK YOU FOR THIS VIDEO! Excellent WORK! GBY.

[@armeddiver]

Thank you for the video. It was extremely educational and I learned a lot. However, I must confess that I don't own a 5.56 or a .223 of any kind and probably never will, but I did enjoy learning the differences and seeing the data. Again, thank you for the video.

[@plow9133]

I been loading 223 for years and use so called 556 brass and 223 bass. Only problems i have with either 556 or 223 in primer pockets on both, they seen to last about the same for me, and every once in a while I will have a split case at the neck, but primers pockets usually go first on both and getting maybe 7 to 10 reloads on one case, i do use a no go, go gauge on every case be for loading and i do anneal, every time

[@EchoSigma6]

I just buy what I can for the cheapest price for range days. Lately it’s been Russian.223 which functions fine on my sporting rifles with the standard trigger. I do have the good brass case 5.56 stuff for home defense, this video reaffirmed what I heard before.

[@romak4756]

Russian crap with bimetal bullet will destroy your barrel

[@RodgerRamjet]

just found this channel... will be watching/searching old vids for tips n tricks.. ! ! great video, full of what, how, why.etc... "Pressure BONES... PRESSURE ! ! !".... almost nobody is gonna get that... lol..

[@liberTvalance]

I was always told they basically the same except for chamber pressure. Great vid.

[@russ3022]

I use Lyman's 50th edition reloading handbook. It combines 223 win and 556 nato in the same specs. I load to around the middle of the specs and haven't had any issues. Seems to me like the same specs are going to generate similar pressures, whether I call it 223 or 556.

[@t-bfr45-70]

556 truly is just a 223 with a 60+ grain bullet trying to push to 3000fps. When attempting to achieve this thay had issues with pressure from the longer bullet length and weight so add length to the throat to lower pressure back to what the time they considered more safe.

[@karatos]

Yeah, I have been telling people for a decade both are totally fine to use. I even tried to put it in the manual when the company I work for started their line of rifles and I was asked to write the manual. Our legal department cut it out!

[@chuckvan1568]

Exactly! I shoot my ammo in all my rifles. I have an early Colt AR-15 with a .223 barrel mark. It shoots 5.56 just fine....

[@karatos]

@@chuckvan1568 the chamber is heavily supported on both because of the design of the system. It makes no difference. The pressure differences are minor and the guns work fine in both configurations. I've got 5.56 and .223 chambers and shoot both .223 and 5.56 in my guns and I've noticed the 5.56 is less accurate in .223 chambers than .223 but that's about it.

[@tomacton6718]

great video on the differences ( and not so differences) between the two. have fired thousands of NATO rounds in both modern 223 Remington chambered and 556 NATO chambers with zero issues.... ever. those were both 55and 62 grain projectiles. i do not use the 69 grain or higher in 223 barrels tho, as encroachment possibility is real with the tighter free bore. the 6,000 psi bump still leaves a good safety margin way under factory high pressure proof rounds; 70,000 psi.

[@langleyj8199]

It’s all about what rifle manufacturer recommends. Good video.

[@willyjimmy8881]

Do you think the extra feebore is just the military's way of ensuring it can run a variety of rounds with not always perfect dimensional accuracy?

[@davidregal6831]

I remember reading that it was to allow for a specific round where the bullet itself was slightly longer than standard 55gr, may have been a tracer round but I am not 100% certain. I will look to see if I can find the actual source for that information, but it would make sense. If the actual bullet length exceeds the standard length from the end of the casing, I would assume one way you can compensate for that is by increasing the free-bore before the rifling. I am far from any kind of an expert as a quick aside.

[@davidregal6831]

Of the information I've found for the L110 NATO and American M856 tracer, the twist rate (1:7) is more significant than the free-bore size, and the difference in size between that and a .223 bore isn't specifically due to the L110/M856 round specifically. In fact the differences in the actual bullet size between standard 855 and the 856 tracer seem to be negligible as far as what sticks out into the chamber (most of if not any of the increase in length is inside of the casing), but I can't say for certain whether or not the difference between the two bullets had any impact in the design of the free bore dimensions. I can't find any information right now that indicates one way or another so i defer to people who actually know what they are talking about.

[@unclenick222]

@@davidregal6831 I believe you are correct. For the M856 tracer round to start out with the same ballistic coefficient as the M855 (our equivalent to the Belgian-developed SS109) it is supposed to trace for, it has to have similar shape and weight. The burning of the tracer pyrotechnic material sheds weight, of course, so it actually starts out a little heavier (63.7 grains) then gets lighter as it flies. This is apparently the compromise the military landed on to keep the round at least close to the trajectory of the M855.

[@waptek2]

2 words , lowest bidder

[@johnnash5118]

@@davidregal6831 Specifically, not “bullet length,” but shank length to ojive as the true bullet seating surface to the lands.

[@blackhawk7r221]

If we go way back in time before all of this mix and match aftermarket stuff, the basic idea was that big army liked the .223, but wanted to toughen it up to ramp up velocity a bit. The brass webbing was thickened, and .025” primer metal thickness was used instead of the common .019”. Staked in. And of course, the neck length was a tad different. A 1965 era .223 has a much lighter case than a M193 5.56 of the same era. The 5.56 did have about 250 fps faster velocity, and more chamber pressure. Army FM’s of the time fully explain the ammo. But today, the waters have really been muddied. If you want to know the specifics of our military 5.56, refer to our current manual, FM 3-22.9. It will answer every question, from ballistics to pressures (according to their method).

[@freedomliberty5525]

There are 3 versions of FM 3-22.9 I would recommend all 3. (FM 3-22.9 RIFLE MARKSMANSHIP M16-/M4-SERIES WEAPONS August 2008, and FM 3-22.9: Rifle Marksmanship M16-/M4- Series WITH CHANGE 1) Plus the publication that supersedes FM 3-22.9, 12 August 2008 (FM 3-22.9 Rifle and Carbine May 2016 Headquarters, Department of the Army.) I don't own a 5.56 as of yet I am still debating whether to build one or not, either way, great info, and easy research. Thank you.

[@blackhawk7r221]

@@freedomliberty5525 I would say grab a low cost AR from Palmetto while we still can. If for nothing else, just to own one.

[@freedomliberty5525]

@@blackhawk7r221 LOL, you and I think like, because I did check out Palmento and that is what put in head to build or not. Currently, I just need to find a nearby FFL. In fact I am just little over an hour from Palmento's warehouse, maybe time for a road trip. I did end up buying a SIG Sauer Buckmaster 3-9x40mm Rifle Scope BDC Reticle, Blk - SOBM33001 from them around Xmas for $90 bucks to go on a 10/22 I inherited last year. Overkill, but it is awesome. I also bought Bushnell Trophy XLT 4-12x40 DOA Reticle SFP Rifle Scope, Black - RT4124BS11 for $70 bucks at the same time. LOL nothing to put it on yet but maybe a new prebuilt 5.56/223 will fit the bill. Thank you, for the reply.

[@blackhawk7r221]

@@freedomliberty5525 I was stationed at Ft Jackson, so we were in the store regularly. Take the road trip. Often, they will stack up “blemished” AR uppers and lowers in plain brown boxes on pallets right on the floor. Like $100 off list price for a paint scratch. If nothing else, just grab a lower and do the paperwork. You can order the rest.

[@freedomliberty5525]

@@blackhawk7r221 Cool, thank you, I love springtime which is always a great excuse for a road trip.

[@jillbluerei4806]

Another great video - thanks. The only missing data would be the primer and powder types - undoubtedly, the heart of the differences.

[@TonyMontana-lh5bp]

I'll save everyone some time here. The answer to the age old question here is.................they're the same, the differences are negligible. I've been reloading for years. I've had this debate so many times it's silly. Glad to see someone took the time to spell it out here.

[@williamdavis3754]

The difference between the .223 and the 5x56 is this. The .223 is a civilian round whereas the 5x56 is a military round. The 5x56 has a hardened case said to be annulled to keep it from denying during combat and it also has a harder primer to keep from having slam-fire problems. These are the only differences.

[@dingo5208]

Denying what?

[@shannonfritsch6647]

Wow..