1/7 vs 1/9 Twist Rate for AR15

[@bdub0983]

Finally a video with real experiments and no bullcrap. Thank you

[@heyman5525]

Tighter twists are theoretically intended to control heavier bullets by given them more rifling spin, but the issue here is probably yardage. Under 250 yards, the twist ratio is probably undetectable or minimal. These tests should be done at 300+ yards.

[@NortheastSurvival911]

I live in the middle of New Hampshire and if you can find a place where you can get a 300 yard shot off you're lucky. There's not too many of them around here. Lot of mountains lot of hills lot of trees things like that. I have my AR-15 which has a one in seven twist rate in a 16 inch barrel sighted in at 100 yards with iron sights. It works for me. I fire all different weights of bullets. And I go between 556 and 223 frequently. At the distances I'm shooting I do not notice a difference regarding accuracy. I would like to find a few places where we can shoot without being bothered up to five or 600 yards and I mean there's a handful of them around but it's private property and it's a matter of going there and then getting a hold of the landowner. And a lot of people these days really don't like it when people they don't know are shooting on their property or they just don't like guns at all. 🤷

[@jakewhite3163]

What’s the point of shooting 300+ with a 223 💀

[@heyman5525]

@@jakewhite3163 Yeah, not much really.

[@Seasniffer1969]

@@jakewhite3163 that's like saying what's the point of shooting a 22-250 past 300yds. .223-5.56 is still screaming past 2400fps from a 20" at 300yds

[@jayklink851]

You know, the was a retro rifle being produced, 1/12 intended for 55 gr. However, people went berserk, they insisted on having a 1/7. The thing of it is, the military only used 1/7 barrels for a specific tracer round, it's a keyhole launcher for 55 gr. Long story short, the company switched to a 1/7 barrel. The customer is always right, even when they're completely wrong lol.

[@6.8SuperDutyDriver]

When the M16A2 was developed, it was originally going to have a 1 in 9 twist for the new 62gr. M855/SS109 (green tip) round. However, the 1 in 9 twist wouldn't optimally stabilize the longer M856/L110 tracer round. That's where the 1 in 7 twist came from. I have AR/M4's with 1 in 7, 1 in 8 and 1 in 9 twists. My 1 in 9 shoots 55gr. to 69gr. bullets great (haven't tried any lighter or heavier). Both my 1 in 7 and 1 in 8 shoots 55gr. to 77gr. bullets just as good. If I had to settle on one specific twist rate, it would be 1 in 8.

[@metabang03]

Comment ride... to me the faster the twist the more damage that occurs in a soft target.

[@markmlinar1511]

You've proved that each barrel needs it's own load. The same load in an identical rifle will be off and is why I started reloading. Thanks for this video as it's proof that nothing is equal and the internets need that.

[@phantomsurvivor6169]

Agreed.

[@4gbmeans4gb61]

Most of what you are saying is true. But doesnt the distance matter on this more then anything? Im guessing the closer the target the less this matters, and the farther away the more it matters?

[@freedomlover425]

4GB MEANS 4GB You could be right. If I get the opportunity to test at 400 or 500 sometime I may try it again. Thanks for watching!

[@hawkeye4545]

Wouldve like to see this with 5.56 ammo since thats what the rifles were chambered in.

[@kn761]

If bullets start out stable then they will continue to be stable until they hit something.

[@Meditech509]

K N not necessarily. Once wobble is induced it multiplies at range.

[@kn761]

meditech if wobble is induced then it didn't start out stable did it

[@HiVoltish]

The over-stabilization is in regard to damage done to flesh when bullet hits. If bullet is too stable it will not tumble when it strikes. The issue is not just accuracy.

[@tedundercarriage8183]

5.56 fragments, it doesn't tumble until around 600-800 yards. Speed kills

[@NortheastSurvival911]

You don't always need a bullet to tumble to do damage though I mean that shock cavity is pretty nasty.

[@NortheastSurvival911]

@@tedundercarriage8183 it only fragments if it hits bone or something hard. Going clean through the damage is caused by a shock cavity. Or penetrating an organ. Or a combination of both.

[@tedundercarriage8183]

@@NortheastSurvival911 That isn't the case, look at military studies on projectile speeds. You can even look at balistic gel tests where there's nothing for it to hit, it still fragments over 2200fps

[@erniewalden3050]

Thank you for showing this. I allmost traded my 1. / 9 twist for a 1/7 twist. I like my smith n wesson MnP sport 2.

[@NortheastSurvival911]

Another factor that people are forgetting to is your overall accuracy with firearms in general. Some people just can't hit air no matter how bad they try other people are good with whatever you give them. So a lot of that has to do as well with the individuals accuracy. I mean overall accuracy across the board regarding their knowledge of how to shoot a firearm. For tests like this optics definitely help. And perfect atmospheric conditions.

[@vitom50]

I have owned three bolt action rifles with a 1-9 twist for years without any problems up to a 69 gr bullet. I just never tried anything heavier. So when I decided to build AR15's, I went to the 1-9 twist barrels. I have one 20 inch, and one 16 inch, 223 Wylde barreled AR15's. I like them.

[@TonaldDrump686]

1:8 to rule them all.

[@JohnSmith-jt3bh]

Right Meow! Thats what I use.

[@codebebop]

LMFAO !!!!! Best comment on this video!!!

[@mikeymike2552]

Right Meow! Just got a 1:8. Haven't shot it yet but I can't wait

[@MikeDMays]

MY 1:8 is amazing! I can buy cheap, expensive, hand load or just whatever and it fires all of them sub MOA at 100yds! I don't buy into the hype but I love to hear what's being said when someone has a flyer or a shot that's off just a bit. More times than not I have found it's a improper trigger pull or someone removes their head from the sight picture just to see where they are hitting. Anticipation will ruin a shot every time! I am not a pro by no means but I have years of Archery experience and great trigger control. I don't have the camera equipment to back up what I say but I promise you at 100 yds if your shooting from a secured fixed platform that will absorb the recoil and remain on target after a shot it took then each of the following shots should be sub MOA or just at 1" Quality ammo is key! many other factors play into this as well but I still think most every AR will shoot sub MOA @ 100yd

[@mikestollov]

Add me to the 1:8 fan club. Yes sir!

[@VailJohnson]

I think all these videos are looking at the wrong element; it's not about the accuracy, it's about the terminal ballistics; what does the bullet do when it strikes the target? In soft targets, 1 in 12 and 20" barrel is devastating with a 55gr fmj. 1 in 7, 16" barrel, not so much. That is where the heavier bullets are useful.

[@williamfotiou7577]

That’s really a fantastic and unexpected outcome. I’m amazed at the 1/9 . I’ve never shot anything over 69 grain in mine for reasons mentioned. Thanks for a great video, bud!

[@wymonwatson1309]

I've shot a fair bit of 75gr from my 1-9 they stabilize fine. All that said I truly believe the slower twist rate is better if your not going to shoot anything over 75gr.

[@stevenharleysh]

I own rifles with both twists and agree with your findings. Thanks for the post bro!

[@Marcus2750-u1t]

I own multiple ar’s setup for all different things...... I use 1 in 8 twist on all of them. They love everything..... 40 grain to 77!

[@franciskaras7425]

Love my CBC 1/8 barrels.

[@Marcus2750-u1t]

@@franciskaras7425 Im more of a lothar walther barrel guy myself…… I have their barrels on all my stuff.

[@wiessambayoumi4977]

223/556 1.9 twist, 16" barrel. 62 and up to 65 grains will always score a robin hooding shots very accurately and the results is very satisfactory.

[@WestDesertShooter]

Dude, this is a great comparison video! I realize you were just shooting the two guns you had available but I really like the group comparisons. I wish I could see hand loaded ammo from the same brand and length barrel. Awesome job!

[@SnipetsofTime]

that was a 37 second intro

[@matthewdiehl1647]

Yeah like no shit, u like guns, huh?

[@Buzz215-1]

a shhhhitty one

[@m.w.guidry8733]

Absolutely practical information displayed via simple demonstration. As inferred in video, your mileage may vary, but there are more important things to consider than just twist rate and projectile weight. Find factory ammo that works in your setup or tune a hand load for ultimate results.

[@AloysiusDevadanderAbercrombie0]

Thank you for this video. I learn better when there is something I can read not so good by listening. Video was a huge help thank you

[@bruceinoz8002]

1:7" is the "mil-spec" twist rate. Why? SS-109 / M855 will stabilize in a 1:10" rate in MOST places on the planet. Remember, though, that "mil-spec' means that it has to work EVERYWHERE from Death Valley in high Summer, to the North Pole, (where the air is denser and has a greater aerodynamic effect on the bullet). HOWEVER, the 1:7" twist was also absolutely necessary for another "military" reason: TRACER projectiles. The L-110 / M856 tracer bullet is VERY long, compared to the "ball" projectile. Thus it MUST use a tighter twist just to stabilize that LONG, but not much heavier than Ball, bullet. Note that, back in the early 1970's, the USAMTU were using 63gn Sierra Spire-points in match-tuned M-16 rifles with 1:12" twist barrels. The 63gn Sierra is a whole EIGHT grains heaver, but about the same LENGTH as the 55gn M-193 Ball projectile, so it worked. Ditto the Hornady 60gn HP, a superb bullet!. Now, not a lot of folks are going to be heaving M-856 tracer down-range, from an AR platform, be it civil or military. HOWEVER, it DOES happen on certain military occasions. More specifically, see the M-249 "SAW" / LMG / MINIMI, which is fed, as standard, linked ammo packed 4 ball, one tracer. Hence; 1:7" as a "Universal" military twist-rate for 5.56mm NATO ammo.IF you want to use extra-slinky VLD type bullets, you must consider tighter twist rates; probably 1:8". It depends on your circumstances. Note also that many longer bullets cannot be seated out and still feed from standard magazine; Overall cartridge length is important. LONG bullets, like a tracer, seated deeply in the case because of OAL issues, will require a totally different propellant type and quantity to even come close to matching the trajectory of a "normal" bullet There is, as always, a further catch. Mil-spec M-855 / SS-109 will be OVER-STABILIZED in a 1:7" twist barrel. It starts to get messy at around 500m because the super-fast-spinning bullet is trying to stay on the line of departure, whilst aerodynamics and GRAVITY are truing to force it to follow a parabola. At 20" barrel velocities, the bullet is "off-line" with the ballistic track and will be eventually forced back in line by aerodynamics, somewhere between 400 and 500 metres. It is this "random" attitude adjustment that produces proportionately larger groups at 500m than 300m Note that "carbines, like the M4 and the 16" barreled version of the Steyr AUG, do NOT have this problem. WHY? because the lower muzzle velocity also generates a SLOWER spin rate (revs / second) and thus a reduced "CENTRIFUGAL" STABILITY. The slower moving and slower rotating bullet from the "carbines" micro-adjusts at shorter intervals and thus, at 500m, will often out-group a 1:7" twist rifle with a 20" barrel.

[@bwana3006]

Bruce in Oz holy cow very interesting and may i politely ask how do you know this?

[@carbonfiber8071]

@@bwana3006You can ask all you want.

[@johnlong384]

I like to thank you for your effort$ explaining the twisty details and will see how my new 24" Wylder Bull Barrel will behave during the scope adjustment as soon as the wind will come down in SW New Mexico one of these days - take care & try to stay out of trouble!

[@freedomlover425]

Thanks and I hope it does well for you!

[@donniedarko1345]

You covered exactly what my friends were talking about tonight at the bar.

[@luketilley9137]

A good friend of mine has a 1:9 and it's a tack driver with 62gr ammo. I was impressed.

[@Me2Lancer]

Thanks for the great tests and explanation. I liked and subscribed. Good to see you busting these myths. Looks to me like the differences between 1:7 & 1:9 are negligible. I agree with your alternative explanations.

[@cannonball666]

The M16A1 was made with 1-in-12 twist to shoot 55gr. The bullet did not keyhole UNTIL impact making it more lethal than the more stabilized ARs of today. The Viet Cong feared the black rifle for this very reason. And yes, it was still accurate as hell.

[@tobyn7649]

I agree, the big difference is realized at 1:10 rate and 1:12 rate with the heavier bullets. It just does not have enough time to stabilize the heavier bullet. Great video! Thanks.

[@Brykk]

These are the reasons im so glad that 1:8 twist has become so much more popular since this video. My chf 1:8 twist rate barrel is getting me good consistency out to about 425 yards with about any weight. I get roughly moa with any decent quality ammo.

[@imhigh0013]

😂 glad you mentioned it... was gonna type 1 in 8..... 😊

[@MikeMikeActual]

Both are very good twist rates!! They're pretty much the same barrels!!

[@jarrettm7043]

Whindham weaponry make awesome guns

[@MiddleOutdoorsman]

At what range was this test done? I just experimented this this last weekend with a 20" govt profile 1/7 barrel and my results were dramatically different. Long story short, at 100 yards, I didn't see much difference between 55 grain, 69 grain, and 75 grain ammo. However, at 200 yards, with no wind to speak of, the 55 grain grouping (if you want to call it that), opened up dramatically with 8 to 10 inches between shots, while the 75 grain produced a 2 inch group.

[@GaragebuiltOriginal]

Former Horseman that's exactly what I would expect to happen.

[@HIMcules2112]

from my experience if I'm shooting any further than 75 yrds i go with a heavier bullet, boat tail open tip match 69 grain and up. 75 yrds and in i stick with 55 grain cheap ol fmj. of course every gun is different but just my 2 cents

[@user-bo8yt4uc8b]

My understanding of over stabilization is that the over stabilized bullet will still be stable after hitting a man, but it’s preferable that the bullet loses its stability at that point to be more effective and cause more damage. That’s why Stoner wanted to have 1 in 12” twist rate to barely stabilize the 55gr bullet, but only when the bullet was in the air.

[@orlandow1723]

Sami Anttila overkill..yeah!!!

[@stevenwatson3496]

That actually sounds reasonable since the 5.56 was very effective when it tumbled and less rotational force would make it more likely to do so.

[@Archimedes616]

I believe some of the early AR-15s actually had a 1 in 14 twist.

[@michaelwaller4179]

I don't know just learning but I think at a longer distance you might see a difference .

[@michaelw.urbansr.8617]

your absolutely right! As you shoot out further and further away the bullets tend to twist and yaw, and tumble so i truly think the 1-9 will do better for the heavier rounds? and the 1-7 for the lighter like the 55Gr which will stabilize out to distance in a 1-7.just saying and im no expert believe me! lol

[@Nick-xe2hu]

Your 55gr Sierra BK in the 1:7 twist found the node of the barrel. If you reloaded this round custom tailored to your barrel you can pull that .89" grouping in even tighter to sub-1/2". I taped a U.S. Dime (coin) to a target at 100 yards and put 2 rounds through it without breaking the edge. I wasn't able to do that till I reloaded and tailored the round specific to my barrel. Thats where reloading really shines. Rather than buying so-so accurate ammo at whatever the going rate is, you can instead construct a far more accurate round often times cheaper. Load data specific to your barrel is added value if you sell. Its crazy the effects of the smallest detail can have. .1 grain more or less powder, or .005" longer bullet jump or seating depth can change the whole dynamic.

[@davidshettlesworth1442]

Thank you for this excellent comparison video. Carry On Sir!

[@Lehmann108]

1:8 is pretty much is the sweet spot for almost everybody.

[@terrylynne8208]

VERY TOUGH TO FIND 1-8 Unless you buy custom for $350.00. Ask me how I know.

[@echoesofmalachor3700]

Barry Lynne ballistic advantage, Aero Precision and Odin works are 3 companies that make 1:8 off the top of my head. I have the BA 1:8 .223 wylde and it’s amazing for the money. Paid $170 on sale. Can get it for low to mid $200’s any given day

[@CoryFugger]

Echoes of Malachor that’s a sweet barrel

[@zpark1130]

Diamondback db15 is also 1.8

[@jordans5674]

I have found that barrel length paired with certain twist rates matters a lot. An 18” barrel in 1/7 will over spin lighter loads, while 1/7 at 14.5” will stabilize lighter bullets perfectly fine, and the opposite spec has the opposite result. 18” in 1/9 stabilizes 52-77 grain bullets perfect whereas 14.5” in 1/9 twist won’t stabilize bullets over 69 grains. The sweet spot seems to be 14.5” in 1/7, 16” in 1/8 and 18” and longer in 1/9 is the ticket to shooting 55-77 grain bullets.

[@Quality_Guru]

Great intel. I especially liked what you mentioned about the effects of barrel harmonics and what you can expect with factory loads. Would have liked if you let us know what distance you were shooting at.

[@wolfgangalpha2941]

Thanks for taking the time to make this video!

[@miniaturefarmer464]

1-12" twist barrels really produce tight groups with 55 grain and under .223 ammo. I have found if you primarily shoot 55 gr. FMJ ammo out of your AR, 1-9" really produces decent groups. If you shoot the 60 grain and up, go with a 1-7" or 8" twist barrel. 1-7" will work fine with 55 gr. and heavier bullets. 55 gr. lead tip bullets will start to disintegrate fired through a 1-7" twist barrel, so use fully jacketed bullets or ELD type bullets in 1-7".

[@douglasj2254]

Great idea for a video on a much-discussed and often misunderstood subject.

[@wacojones8062]

The Original 223 test barrels were 1/14 they did well in Field tests in Nam. The tracer rounds with much longer bullet length failed in the Cold weather testing in Alaska. So Until the M885 rounds came out all were barreled with 1/12. The first Tests with the Tracer load to go with the M855 with 1/12 twist showed very erratic results so various twists were tried ending with 1/7 to stabilize the very long tracer bullet. M885 62 gr and 55 gr M193 both did ok in M16A2 I Fired while in training in the reserves. The M855 groups were very bad in M16A1 with 1/12 twist with tracers being almost completely unstable sometimes hitting the ground at around 15 meters when fired from the Prone position. Good testing with what you had to use.

[@OneRoundDown]

I did the same kind of test when i barrelled a 20" with 1:7, NM HBAR. I got similar results from the heavier 62-77gr projectiles at 100 yrds. What surprised me was the .350-.500" groups i got with 50gr ballistic tips, i to thought 1:7 would impart too much spin. I got very similar results from another rifle with a 16" 1:8 with the 50grbt and the 77gr IMI, .50" and 1.10" at 100yrds. It appears that the heavier projectiles need a bit farther distance to fully stabilize and pull into its flight path. Clearly with respect to the lighter projectiles the tighter twist is proving to be a good choice.

[@lizwynaco2222]

I like the approach used to examine both twists.Thanks.

[@PaulJersey]

Very informative. I have two AR’s that both are 1/9 16” barrels. I wanted to keep down my costs by using the same mags, ammo, carrying bags, etc.

[@thebronze8518]

Great vid I have a 16 inch barrel with 1:7 TWIST I got the same results

[@Gath8mm]

Outstanding comparison. I run a 1/9" MKE T43 with heavies 14.5" barrel. Couldn't be better.

[@fomocore]

I have to agree. I have a 1 + 9 and when shooting military tracers at about 400 yards they start to Corkscrew. Whereas the one in seven in my samples didn't

[@factsoftheconfederacy7151]

My rule of though is the 62 grain loads are best in a 1/9 twist. I own a free floated AR (DPMS Recon), it is very accurate.

[@dbmail545]

Had 77 grainers stabilize out of a 1/9" just fine, but the groups opened up a bit over the 1/7".

[@1969plato]

Same here... you just have to know what grain is best for your rifle/twist rate. I bought my first 1:9 and moved up to 77gr, and it's great.

[@bungalobill7941]

I have gotten pretty much the same results at 100 yards. I'm wondering if longer ranges might be more telling. Out to 300, 400, and 500 yards. You should do a test like that. Barrel length would also play a part.

[@PracticalAccuracy]

I've done it out to 800 yards with a 20 inch and 16 inch and was able to stay on target.

[@red9man2130]

this video is the best so far that I have seen to explain the differences between 1/9 and 1/7 twist rates. the term "over stabilize" has to do with the fact that the m4 platform with a 1/7 twist firing m855/ss109 rounds does NOT TUMBLE when the bullet encounters FLESH it has nothing to do with flight trajectory or "keyholing". From what I have read and heard the 1/7 twist rate barrels burn out faster due to increased friction between projectiles and the bore. It is true all things being equal that the 1/7 WILL perform better at LONGER ranges with heavier bullets. Frankly while the 5.56x45 CAN hit at more than 500 yards in my opinion that's really stretching the capabilities of that round. Yeah I know about the 1/8 twist and the DMR rifles used in combat. It was observed in Afghanistan that the m193 ball out of a 20 inch barrel was outperforming the m855 on Human targets terminally. I do prefer a 1/9 twist if for no other reason than barrel longevity.

[@bedlamite42]

Temp and air density play a big factor. They both work fine in warm t-shirt weather. Try this test again in the northern winter with cold dense air and the 1:9 will not stabilize the heavier bullets.

[@muwuny]

I think the main difference is how they destabilise in a soft medium like flesh or gel, rather than accuracy. Look at MAC's video comparing 55gr out of a 1:12 vs a 1:7

[@newdefsys]

I am under the impression that the issue of overstabilization revolves around wound ballistics. The original _OG_ AR-15 had a 1:14 twist rate but the Army wanted it increased to 1:12, despite concerns that the faster twist rate would "overstabilize" the projectile and negatively impact its hydrostatic shock effect. That concern was renewed with the change to 1:7 twist, (the 55gr projectile loses even more hydro-shock effect with the even faster twist rate). But I am an old man and I am recounting old debates from the 80s and 90s.

[@famedad8918]

1:8 is the best overall twist rate for accuracy in everything up to 70 grains. The only reason the military went to the 1:7 is to stabilize the M856 tracer round. It is extremely long round, and the 1:7 becomes necessary to stabilize it. If all they were shooting was M855 ball (62grain), then 1:8 is all that is needed. Actually most testing shows 1:8 is the best twist. 1:9 is just fine as long as you stay 65 grains or below in weight.

[@oliverallen5324]

14.5” barrel is why. Do it out of a rifle length and you’ll see a radically different spread. Thank you for your efforts.

[@kalanipitmon7817]

Why is a 14.5 always 1/7 twist?

[@speedyscraftservice]

great test... thank you for the test and the Info.

[@gilanbarona9814]

In the service, the issue M16a1 had a 1:12 twist. It was good enough for 55 grain ammo issued out of the Philippine State Arsenal. We would average around 2 to 3 inches at 100 yards even with the thin barrels of that rifle. We got to try a few sample M16a2 rifles at the time, with 1:7 twists and heavier barrels. They did slightly better with 55 grain ammo. However, at combat distances, either rifle was more than sufficient.

[@Maryland_Kulak]

Excellent video. Empirical evidence beats logic every time.

[@autumnfragrance6326]

The original M16 prototype had a 1:14 twist. Was increased to 1:12 when they discovered it was unstable in cold environments. 1:9 twist is plenty with a barrel at least 16 inches.

[@Me2Lancer]

Thanks for sharing. Good information. Regarding the non-flyer you mentioned, maybe it was just a bad load or at least a non standard one.

[@NWPreparedness]

I have 1:7 and haven't seen any noticeable difference between different ammo types. Good info.

[@texasviking1]

Average Shooter 76 I just got me a 1:7 barrel I have not shot it yet but I’ve heard great things about them.

[@dobypilgrim6160]

The individual behind the rifle is the greatest variable of them all.

[@pkloehe]

Barrel to barrel also makes a difference. I have a 1/7 twist 16" CHF barrel that loves 55 FMJ and a 20" 1/7 button rifled barrel that hates it.

[@KJ-nw8ge]

Shorter barrel? 1/7 Longer barrel? 1/9 Simple.

[@ETHRON1]

You are right about the amount of variables. Endless.

[@danielgrubb9668]

My experience is that a 1:9 twist produces a tighter shot-group of 55 grain projectiles than even a 1:8 barrel.

[@mauserk98bnz44]

I have a Bushmaster 20 inch Hbar 1-9 twist how far can I expect to hit a steel target 18x30? I will be using a primary arms 1x6 with acss reticle. Should i just re-barrel the thing. I also have a PSA AR-10 in 308 with a 1-10 twist I’ve thought about using for long range up to 600 yards.

[@mr.mikesart7111]

Thank you for this video. Not enough information on this topic

[@bruceinoz8002]

It IS possible to "overstabilize" a bullet. The point of rifling is to spin the bullet to make it like a tiny gyroscope. The critical factor is the atmosphere. Air-resistance (drag' is what causes the bullets to slow don. However, GRAVITY is what causes the bullet to "fall" to the ground. When you launch ANY bullet, it will be traveling (more or less) along a line co-axial with the muzzle at point of departure. These two factors are why bullet trajectories are, more or less, parabolic. The spin STARTS the bullet "on axis", HOWEVER, if the spin-rate is too great, the bullet willtry to STAY on that path, even as gravity is making it "fall. Thus, the bullet axis will, at some (actually, many) points, be "out of whack". Aerodynamics will kick it back into line under "normal" circumstances, however, if the spin-rate is too high, the "adjustment" needed will be bigger. This WILL mean that there is a very big chance that during this "attitude correction" jump, the bullet WILL actually alter its flight-path. The other thing is that the LENGTH of the bullet is the critical factor. The 1:7" twist was developed so that rifles and machine-guns could stabilize the outrageously long L-110 / M-856 TRACER bullet; the SS109 /M855 ball rounds could have easily been stabilized in a 1:9" twist, even in Arctic conditions. Older Military Match shooters may remember the early experiments to tweak a basic M-16A1 (1:12" twist) to shoot "heavier" bullets. There was some VERY interesting work and impressive scores shot using the Sierra 63gn soft-point. Because of its shape, it is barely longer than the MilSpec 55gn M-193 bullet; thus it was stable out of a 1:12" twist barrel. The steel "penetrator" (cough) in the 62gn M-855 means that bullet is somewhat longer AND is launched at slightly lower velocity (thus, in the same barrel, spin-rate), than the old 55gn bullet. Australian military shooters very quickly discovered that the 20" barrel on the F-88 (OZ version of the AUG), was consistently out-grouped by the 16" carbine version at ranges beyond 300m. The shorter barrel's lower velocity produced a slower spin-rate (both have 1:7" rifling), thus, the slower-spinning bullet from the carbine would "micro-adjust" and stay on its original trajectory, all the way to the target.

[@freedomlover425]

Bruce in Oz That's a very informative post. Thanks Bruce!

[@im-oc4jr]

You either have no clue about math or you are talking about something completely different. This is what you said: "The spin STARTS the bullet "on axis", HOWEVER, if the spin-rate is too great, the bullet will try to STAY on that path, even as gravity is making it fall. Thus, the bullet axis will, at some (actually, many) points, be "out of whack". Exactly if the bullet (or any flying object that uses spin for stability) is spinning too fast is it UNSTABLE. There is something call precession. Type in into google search precession definition or take a math class on stability of flying bodies.

[@bruceinoz8002]

I probably could have worded that better, and I am also VERY aware of the phenomenon of "precession". And, no; I don't have a maths or science PhD, unlike my wife. The spin acts to maintain the bullet on the line of departure. That this line of departure, is rapidly overtaken by the bullet adopting its characteristic "parabolic" trajectory, is the key point. IF the line of departure at the muzzle is, say, fifteen degrees above horizontal, because of the spin, the bullet will "try" to stay at that fifteen degrees. However, as the bullet follows that trajectory, (complete with the spiraling precession AROUND that trajectory), at some point, there WILL be an angular difference between the alignment of the bullet and a tangent to the trajectory at that point. The theoretical ideal is to have a bullet traveling at a TANGENT to the actual trajectory at ALL points along that path. To achieve this theoretical "perfect" relationship, the bullet MUST constantly change its "attitude", aerodynamically speaking. This not quite being a perfect world, in which perfectly concentric bullets are fired up perfectly concentric barrels, departing via perfectly cut crowns, things will be a bit different. Thus, at regular intervals along the trajectory, the aerodynamic forces (via the "shock" cones), will try to "adjust" the bullet back into a better aerodynamic alignment. If this happens in tiny increments and at high frequency during flight, the bullet will travel very closely to being constantly tangential to the trajectory. The faster it is spinning, the more a bullet will resist the aerodynamic forces and the further apart will be the necessary "adjustment" jumps. Thus when they happen, hey will be bigger and the time taken for this adjustment may well see the bullet on a slightly different "flight-path". Imperfections in the construction and static balance of the bullet are another potential contributor to excessive precession. The vintage "Greenhill's Formula" is a good start for calculating twist rates, but it was developed back in the days of relatively short, solid lead bullets fired at velocities below 1200 FPS. By the time you get to a boat-tailed, hollow-pointed, jacketed bullet, launched at over three thousand feet per second, it gets a bit odd.

[@troyb.4101]

Does a buller spinning fastest, slow it down? I would think it's enegry used. Where as a bullet spinning less might be traveling faster. That's what I came up with. Does it make a difference. To me not at all , as I'm not a professional shooter and I am not going to go out and buy $1500.00 scopes for a $700-$1,000 gun.

[@skeptikul270]

I would think its more to do with length of barrel than velocity. A barrel 4 inches shorter gives up over half a rotation in a 1:7 twist..and exactly half rotation in a 1:8 twist 16/20". So maybe the bullet in the 16 inch barrel just wasnt spinning as fast because it didnt get to spin almost 3 whole revolutions like in a 1:7 twist 20 inch barrel.

[@mk45gunnr25]

Twist rate is more about lethality in my opinion. That's always been why I prefer the slower twist rates so the bullet will more radically destabilize upon striking the target. The original 1:11 rate with a 55gr bullet was what the heart of the lethality of the 5.56. But of course the Chair Farce ruined the platform over concerns about artic operations. A 1:11 or 1:12 firing a 55gr bullet is what the platform was intended for. I am talking battle applications, not target shooting or other types of range work. 7 or 9? 6 in one half dozen t'other

[@z50com]

Bear Creek 20" SS Wylde Chamber 1:8 Twist ~ It works and works well

[@DoobTube71]

With the AR- platform, barrel twist rate is one component. Length of the gas block is also important.

[@hekkenschutz]

Yeah... after trying different barrels I stick with 1 in 8 or 1 in 7 but what I care about is the 223 wylde chamber for my reloads. Even with proper full length resizing and neck resizing the three 5.56 Nato chambers I had were not all the same size... quite frustrating

[@peterhauer3960]

Excellent video! I think the problem with "over-stabilization" is not reduced accuracy. The problem is light bullets fired with a rapid (1:7) twist tend to shred their jackets upon impact. This causes superficial wounds and a lack of penetration for hunting purposes.

[@mddubtubeyou]

Will it mess up your barrel at all? Say a heavy barrel profile with 1:7 shooting mostly 55 grain.

[@u.p.woodtick3296]

My Sig model 400 is 1 in 7, I’ll have to live with it, suits me fine

[@a.d.3803]

1:8 master race

[@shadowhawk320]

fantastic video, to the point and honest. Do it again.

[@ManOnFire434]

I think it also has somthing to do with how many times the bullet turns in a (14in barrel 1:7 ) (16in barrel 1:8 ) (18in barrel 1:9) (20in barrel 1:10) you get 2 revolutions before bullet leaves the barrel which leads to better accuracy bullet weights and chambers also have a part but mainly i think its the twist rate rate

[@stevelewis7263]

I had a Howa 1500 in .223 with a 1:10 twist, it shot light rounds well but heavier .223's grouped like buckshot with groups of over 12" at 100yards.

[@kn761]

the 69gr SMK is designed to work in a 1/10 twist. it'd be cool to give those a try

[@PARR53]

My own results from a 25m/300m zero using a 16” 1/9 M&P15X was almost exactly the same using both the 55gr XM193 and 62gr M855 green tip both of which are the most common military surplus ball ammo available on the market for the 5.56 NATO caliber. What this means in my opinion is that out to 300m assuming you know how to shoot well enough your POA/POI isn’t going to vary enough within 7gr of projectile weight. I haven’t tried the much heavier or lighter .223 bullets to see how much this holds true from my own rifle yet. It’s cheaper to shoot the 55gr M193 stuff by alittle bit but having the extra steel tip M855 Ball rd can and does punch better so for me I prefer it.

[@kalanipitmon7817]

Shoot, out of my 14.5 1/7 with 55gr i dont even have much holdover up to 300 yds

[@jc-vc7xq]

I may have missed it in the video but what was the distance. Also I wonder if you would see different results out of 18 or 20 inch barrels?

[@markrichardson1657]

jc6621 barrel length doesn't change twist rate.

[@kn761]

no, but it does change the velocity and bullet rpm at the muzzle which will change the stability, or a smaller bullet's likelihood of exploding in mid air.

[@HockeySavants]

a 7" AR Pistol/SBR build...absolutely

[@stevenwatson3496]

K N yeah I was told my 16” 1/7 would spin the jackets off of 55s but they still hit steel at 200 with a nice smack lol.

[@donaldmayoneshot5579]

I have a AR-15 on the barrel it's got 5.56 NATO will it shoot a 5.56x45

[@maxlumens9085]

That's crazy. I've seen a. 223 Remington that's shoots. 223 Remington well.

[@richardalexander5758]

Thanks for the interesting test, confirming my own observations. Yep, my 1:7 barrels seem to like 55 grain factory ammo too. I have yet to try heavy (long) projectiles out of my .223 bolt action, which has a 1:12 rate of twist. The bolt action also likes 55 grain factory loads over lighter (shorter) projectiles, which wasn't what I was expecting going in the other direction.

[@nitrocamcam747]

Twist rate can offer many advantages to heavy or light bullets. But in the end, it's barrel and load specific. I have a 16" 1:9 twist ss barrel that can group .500" with Hornady 75gr BT match, and .335" groups with Hornady 68gr BT match bullets.

[@tadgodsey]

Man, that was a very good video. Nice objectivity.

[@wbvmcgary]

The heavier bullets are longer in length therefore the 1in7" twist will spin the bullet faster and help keep back of the bullet from sagging earthward at long distance. That my friends is the difference.

[@kn761]

wbvmcgary, I'm sorry, but you have the whole concept of bullet stability wrong. That is not what happens to a bullet if it is not stable.

[@12pharro]

wbvmcgary if you drop a bullet and shoot with bore level with the earth at the same time, they will hit the ground at the same time. If anything, overspin with cause a bad bullet to fly apart, fly off into no man's land or drift right due to the Magnus effect, that's why golf balls have dimples, to cause lift, as soon as that bullet has rifling impressions in it, it has drag and airfoil

[@GeorgiaBoy1961]

An excellent study done by FL, but perhaps he has omitted one variable from his study - bullet length. Projectile weight isn't the only variable affecting bullet gyroscopic stability - length is also very important. It would be interesting to see how longer bullets performed out of these respective 1:7 and 1:9 barrels.

[@GBGuns]

Great job! Keep up the good work.

[@freedomlover425]

Thanks for watching!

[@Whalermansteve84]

Graham Baates I have a 1/8 twist on my Ruger AR556 and my 300 blackout. No issues. When the billet is exiting the chamber there is no exact way to tell if 1/7, 1/8 or 1/9 is best. They all basically do the same. We physically don’t see the bullet leaving lol

[@anchorbait6662]

If a bullet rips apart it doesn't mean it's over stabilized. It just means its RPM was too high for the jacket to hold together. They are different properties and shouldn't be lumped together. A super fast twist does have the ability to keep the bullet stable for long enough to have it keep its orientation level with the initial barrel exit so that when the bullet starts to drop significantly.. Like 1000 yards or beyond (ballpark) then the bullet won't be pointed down towards the impact, it will still be pointed to the original aiming point. Like a gyroscope. I think alot of people say over-stabilized when referring to this property of the bullet

[@petergriffin383]

Excellent video! Finally somebody covered this topic well. 100yrds is a good test bed because most people are not taking shots beyond that, and if they are they probably already have their rig set up how they want it. This is great for the rest of us.

[@JayDee-bz2ge]

I think the difference starts to become more apparent out on longer shots. 300 - 500 yards+

[@fredsmith9788]

What I want to know is, if 1:7 is supposed to be better for heavier bullets in an AR-15, then why do 7.62x39 AKM rifles typically have a 1:9.5 or 1:10 twist rate, and why do most .308 rifles have barrels with a 1:10 twist rate?

[@shockwave6213]

Both 1 in 9 and 1 in 7 twist rates will be adequate to stabilize the most common bullet weights (55 grain and 62 grain, namely) inside 300 yards with a 16 inch barrel (barrel length and velocity are big factors), which is where most shooters will shoot and that's why most 5.56 guns use either twist rate. If you're going to specialize your gun for a certain task, choose features accordingly. Someone who wants to shoot 40-50 grain bullets at varmints would do well to pick a 1 in 9 (or 1 in 12 with 20+ inch barrel) twist, while the target shooter flinging 77 grain ammo at distance should pick a 1 in 7. These are generally good suggestions, but like always: There are outlying factors.

[@JacksonMalcolm]

bullet stability has a lot more to do than just twist rates. altitude, temperature and bullet length are big factors. often the most accuracy can be found at the ragged edge of stable, this is why youll see F class guys shooting 1:16 twists and other slow ones. also why youll see guys shoot insane groups first thing in the morning and open up to the .3s by 9-10am.. we have tighter twists that give us more leeway but there are times where youll find that drop off when enough factors compound. berger has a stability calculator that should be helpful to anyone worried about stability.

[@davidortiz173]

I like your experiment! New sub for sure!

[@ung427]

Now if I'm not mistaken, the twist rate has to do with projectile length rather than weight, right? You can learn this as a kid throwing different things.. that's how I did anyways. SO, I always wondered why it always had to do with weight in conversation, because some bullets are made with different alloys.. and hence weight isn't always linearly correlated with length.

[@Bigtrain1]

I will, I'm headed to Colorado for the summer, hiking and bow hunting elk. I'm 200yds from blm land with the next house 50miles north, with plenty of places to shoot.

[@bartblack8054]

where abouts? I live in Denver Metro area. I'm looking for some good areas to explore for shooting.

[@fiveniner507]

Ha! You want friends real quick? Im in Denver too!!

[@Shamrockrancher]

I didn't realize BLM had land up there! I can only imagine what they're using it for!

[@terrylambing4689]

You are the first person to point out there are other variables in different bullet weights, as you mentioned a slight variation in powder charge and the harmonics of the barrel, just know that every rifle barrel can and will shoot differently regardless of twist ratio. The only true test is to shoot groups of different bullet weights and chronograph each shot to be sure each round is shooting the same! you can get a flyer just in a small variation in powder charge which will change MV.

[@BrwnShinobi]

Nicely done!! All I know, each group, each round, under either twist rate; You're taking a target down!! What's the average chest size of a target? lol a foot or more?? Thanks for the video