Converting Your AR15 to .300 Blackout: Instructions and Benefits of The Cartridge

[@christianrorozco5610]

I bought a complete lower and was wondering what my options were as far as calibers. I'm kind of a new to guns so this video had a wealth of info! Thanks for sharing!

[@HSFirearms]

Hello there. There is a ton of information on the topics of calibers to pick from, I may do a more detailed video on this topic this week if we have time. The main calibers I’d recommend for a new-intermediate AR builder in order of ease to build would be: 5.56, 300 BLK, 7.62x39, 6.5 Grendel, 6.8 SPC, .224 Valkyrie. Past that, there are some big bore options but I dont recommend building these uppers from scratch as they require specialized parts; .450 Bushmaster, .458 SOCOM and .50 Beowulf. Each of the calibers I’ve mentioned will work on a standard size AR15 frame, you can also find mag well inserts for pistol caliber builds but that is more advanced and can carry its own challenges when trying to build. There is also large frame but as you have stated you already have the lower so I won’t mention those here, .308/6.5 creedmoor and others being large frame calibers. If you were to ask me in January I would recommend hands down 5.56 as your first AR caliber, but in today’s world having an odd caliber (not mainstream and non-wildcat meaning commercial cartridges are still available) such as the 6.5 grendel or the .224 Valkyrie make excellent choices today. For the grendel conversion you need to change the magazine, bolt carrier and barrel, same as the .224 valkyrie as well which uses a 6.8 spc bolt head. Make sure you get the grendel type 2 bolt head if converting your 5.56 bcg to a new caliber, however I’d recommend purchasing or building a new upper so you have the ability to quickly change back and forth. If you have any more specific information specific to your scenario for use such as optimal range you are welcome to let me know here, over the phone or at our email listed on the HSF channel page and I’ll be happy to provide any additional information. Thanks for watching!

[@HSFirearms]

kzbin.info/www/bejne/g4HbeXaOfrNqerc We answered your question in much more detail in our latest video. Thanks very much for your comment and your viewership!

[@christianrorozco5610]

Awesome! Thanks again for your advice. I'm 99% I'm going to go with a 6.5 Grendel. I will be taking your advice and buying a complete upper instead of piecing it together.

[@SacredWade]

Hey brother... good video but I just have to say it was a little hard to focus on the content with the feeling you were undressing me with your eyes 😭🤡 so I just listened and it was very informative, thanks!

[@tomconley2458]

I like having different caliber uppers and use the same lower.

[@GarrettXPrime]

This guy looks like he would laugh at all my awful dad jokes Great video great information you’ve earned a like

[@Max-ye9xg]

The word the narrator was looking for shooting a 300 Blackout through a small 223 barrel the failure would be catastrophic

[@ledzeppelin1212]

Thanks for the video, man!

[@james5346]

Good video man. Keep up the good work. I needed this info.

[@HSFirearms]

Thanks for your comment!

[@1940restorod]

I like the high security gun cabinet. The white board reminds me of Carl Rove on FOX.

[@letsgobrandon4066]

I wish I was this happy

[@michaelrichardson9675]

What part (s) do you have to change to go from .223/5.56 to 308 Winchester and 350 legend. Does the 5.56 bcg still work for these two other calibers like it does the 300 blackout. And can the 5.56 be converted to .30/.30 and/or 30-06?

[@Driver-ur9mf]

5.56 or 223 is an AR-15 upper/lower. You may also use 458socom or 300blk, or 50beowulf uppers with that lower. 308 Winchester or 7.62 NATO uses an AR-10 lower, 6.5 Creedmoor, 300 WinMag are other uppers you may use with that lower.

[@generalelectric8403]

I just bought a ar15 complete lower and 300 blackout upper. Can I put it together and use it.

[@HSFirearms]

Essentially yes, however there are legal considerations to assembling the two pieces in the form of "27 CFR § 478.92 - Identification of firearms and armor piercing ammunition by licensed manufacturers and licensed importers." and whether you meet the definition of manufacturing. For us as an FFL to assemble the two, we are required to mark the lower receiver with our trademark and address, and pay the 12% Pittman-Robertson Act manufacturing excise tax. As an individual if you never transfer the firearm to another individual then you will have no issue, but should it be transferred, it is still legally a lower receiver not an assembled rifle / pistol until a manufacturing step is completed by a licensee.

[@knjpollard]

Awesome vid. Man i started out excited at how easy this, but then I thought damn what if I accidently chambered the wrong rounds since the mags are the same. I would probably have different color mags for 300 vs 556 to keep me from blowing up my gun and facing injury.

[@ledzeppelin1212]

That's a good idea! Is this really a concern though? I'm guessing a .300 wouldn't even chamber in a 5.56 barrel and a 5.56 in a .300 barrel would just blow extra gas out the barrel. But still better to be safe than sorry after all!

[@josepholinger130]

I just ordered the full 300 blackout upper for my. M&P Sport2 easy swap

[@cadenunley4580]

I’m trying to do the reverse but idk how (.300 blackout to .223)

[@highcosmonaut7255]

What a waste .300 Blackout is trash.

[@wilhemalmodovar8910]

@@highcosmonaut7255 Not really, just pricey, but in my case 5.56 isn’t a hunting cartridge so it’s either get a 30-30, 6.5 Creedmoor, or .300 BLK dedicated rifle, or just swap my 5.56 barrel to a .300 BLK barrel

[@highcosmonaut7255]

@@wilhemalmodovar8910 Still hate it, it's not a very good hunting cartridge at all. I'm glad I got rid of mine.

[@paullinn1405]

Thanks for the great content

[@luhsnaypaa3376]

so i can put 300 black out upper on my ar15 lower whit out changin bolt , firing pin , buffer?

[@josepholinger130]

Will definitely keep eye out on the gas carbon

[@markrich8888]

Ok, I have a Springfield Saint AR pistol in 5.56. I can simply swap out the barrel to convert to a 300 blackout without messing with the gas system, correct?

[@HSFirearms]

Technically yes, but depending on which saint model you have it will be more complicated than that. Do you have the fixed A2 front sight gas block or is it the free float model? If it is free float it would be a simple conversion, but otherwise you would have to drill your .300 Blackout barrel for those pins and I don’t recommend that. The other thing which may or may not be an issue for you is if it uses mid length gas I’d swap that out since .300 Blackout prefers pistol gas or in some cases carbine gas but mostly pistol gas, in carbine or longer gas you sometimes don’t have enough pressure to cycle the bolt and that can cause issues. I had a carbine length .300 BO and had to get the nemo light buffer spring to get it running, mid-length wouldn’t be worth a try because it’s way too far away to do any good for you and it would short stroke every round.

[@markrich8888]

It's the free float model so the conversion should be easy and since I bought it as a pistol it has the pistol length gas system. Thank you for your help. There's very little info out there on this topic with the pistol I have.

[@markrich8888]

@@peacevhunkk I bought it new as a pistol with a 7.5 barrel. I'm aware of the laws.

[@GunSlingerKe]

@@peacevhunkkyou don’t know what your saying

[@stripervince1]

I just got a pistol in 223 wylde and gotta find a complete 300 upper. Think I want a 5 inch veritas

[@535tony]

Good info here, thanks!

[@richardgreen2570]

I get a strong Full Metal Jacket, feeling.

[@NistaDGB]

I have a custom built ar15 and the lower has a local gun smiths company ingraved so I don’t know the make but how would I be able to tell if my 556 lower will work with 300 upper & barrel? I’m probably just gonna order a whole separate lower lol

[@HSFirearms]

If you have a standard size 5.56 lower it's the same size as a .300 blackout lower and will be compatible with your .300 upper receiver. The magazines are the same as well which is where the concern comes about making sure you are using .300 BLK ammo in your .300 BLK upper instead of 5.56 when the mags look identical because the are interchangeable. The lower can actually be marked anything, it has to do with what magazines it accepts (5.56 spec, .308 spec, 9mm) as to whether it works with the caliber you are trying to attach to it.

[@NistaDGB]

@@HSFirearms unfortunately I live in the non free state of NY. So my first rifle happens to be “safe” lol. So by that I mean the dealer I bought it from has the mag pinned so it’s compliant and I’m not even sure how honestly. I’m afraid to ask him about it being it’s illegal here for the release to be functional. Smh but thanks a lot for the information I really appreciate it!

[@johnniel5465]

I cant help to notice but is that a fnx 45 tactical u got there?

[@elvynortiz3456]

Good video thank u 🙏🏽

[@gamehopper111]

300 blackout and 300 "ACC" blackout are same ammo?

[@HSFirearms]

Yes the full name of the cartridge is .300 AAC Blackout, which started as the wildcat cartridge “.300 Whisper” and later renamed when AAC took the cartridge mainstream.

[@saltybuckeye]

Good information thanks

[@joehunter5914]

What If i buy a complete 300black out upper and slap it un my 556 lower?

[@clayman71497]

It'll work, 300 blk and 556/223 use the same lowers and magazines and bcg, everything but the barrel is interchangeable

[@TexasBoy76]

You could just buy a complete 300 blackout upper with a pistol length gas system and put that on a 5.56/223 lower can’t you

[@HSFirearms]

In most cases, yes. There may be minor problems with the gas system such as imperfect ejection angles, but these can be fixed with a different buffer weight. If you go with a carbine length you will most certainly need a lighter buffer weight, but pistol length usually does not which is why it’s so popular in .300 Blackout.

[@AfcaptKappa]

You may also have problems with ATF if you put a pistol length AR 300 on the Ar15 lower . You will have to have at least a 16 inch 300 upper!

[@realtruenorth]

​@@AfcaptKappahopefully Trump gets rid of the ATF in his next term.

[@Confad22]

Good video, thank you

[@HSFirearms]

Thanks for your comment!

[@MoeDenlilbii]

Is that dude from full metal jacket?

[@salimsopari]

great video!

[@HSFirearms]

Thanks for your comment!

[@eperry3585]

nice video 📹, thank you

[@HSFirearms]

Thanks for watching!

[@joehunter5914]

Adjust gas block will do the job

[@Max-ye9xg]

A 223 shot through a big 300 Blackout Barrel will very likely shoot it and not explode ,,,, but a blackout bullet through a 223 Barrel has nowhere to go and will explode the bolt in your face

[@castorjones2455]

.300blk rounds are expensive.

[@Crowbaen]

This guy looks like a tow truck that I know

[@MrChikoSticks]

He’s “slow”

[@ccg2483]

No clue wtf you are trying to explain, Also speak up a bit. you have to understand. There are some people that are completely new to this and I must say that you are not explaining yourself clearly break it down pretty much like you were talking to someone with zero experience with guns, because there are people out here trying to learn from step one. There is just too much mumbo-jumbo talk just get to the point.

[@jayroc1158]

Buy a completed AR-15 lower (do NOT use a lower from a rifle bought completely assembled from a manufacturer bc of legal reasons ((unless if it was an AR pistol, then you're fine)). Those are transfered over as "rifles" and have to stay a rifle) then buy a pistol length 300blk upper and just pen them together. I wouldn't recommend going over 8" bc the round was designed to be shot from a suppressed pistol with subsonic ammunition. If you only want to use supersonic ammo, stick with .223/5.56 There may be gas tuning involved or a buffer swap.

[@jayroc1158]

Also, the lower must have a pistol brace; not a rifle stock.