re: Official AR-15 thread

Is it still giving him a problem? Does he know how to take the bolt apart so he can clean under the extractor key?

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Brand new mag.

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If it never did this before, Id point to this.

hey guys, my dad is having a similar issue. he just bought a .300 blackout rifle/carbine length barrel (anderson manufacturing). he's telling me that the gun isn't cycling properly. it'll eject the spent shell, but it won't chamber the next round.

he can manually cycle the next round, but it won't do it automatically after each shot. i'm thinking he bought sub-sonic ammo by mistake so it's not getting enough "umph" to push the bolt all the way back to cycle properly. it's getting just enough to eject the spent shell.

did a little research and it could be that the gas port isn't quite big enough. which does but doesn't make sense. how often is it that the gas port on the barrel is too small? also, it appears that it doesn't have an adjustable gas block.

i'm over 600 miles away from him so i can't really investigate it like i want to.

here's the upper he has.
LINK

I use the same buffer and spring

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The gun is designed to run with a silencer which creates back pressure to eject subs. With supers it should run fine.

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Yeah, that makes sense, and probably just the ammo that's the problem.
If you've ever shot blanks through an AR, or M16, you have to put a clamp in the muzzle to get it to cycle, because you don't get enough back pressure. Same thing.

He sent me a picture of the box of ammo he was shooting.





spent $30 for that box.

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I don't know a damn thing about the .300, does it use the same buffer spring as a .5.56, or does that have to be changed too?

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I can answer that question with a solid "YEP!".

The .300BLK design, at its core, is intended to be able to take a standard 5.56 platform and function with absolutely nothing more than a barrel (and associated gas tube) swap and retaining all other components. This is where practice diverges from design.

Generally, the same spring will work, but the .300BLK tends to have higher recoil energy, pistol length gas systems, shorter barrels, etc. An H or H2 buffer MAY make a particular weapon cycle better, be timed better, fire more smoothly, less harshly, etc. Suppressors and the increased backpressure you often see with them and subs vs supers each change the equation as well. It's one of those things where you start normal and run through everything you'd like to shoot, see how the weapon performs, and adjust accordingly.

I'm building one that will eventually have a dedicated can mated to it and will never be fired unsuppressed once the can gets out of jail. I expect that I will want to make adjustments to the buffer and maybe the gas system at that point, but that's not a given. Until I know for sure, there's going to be a standard carbine spring and buffer in there.

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I think it's missing something, besides a can, longer hand guard?

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The forward assist!

I personally like the handguard to come up just short of the shoulder on the barrel threading so the can fits up nice and tight to the handguard. If I'm not bringing the handguard up tight, I also like the hanguard to have an ID > 1.5" and be an inch or so shorter than the total length with the can attached to tuck that bad boy under the guard. It lets you get a longer grip on a shorty with a suppressor, though it can get a little warm if you're shooting a lot and not wearing gloves. If you're shooting subs through a user serviceable can, though, the can under handguard approach isn't so great if you can't remove the handguard easily so you can get to the can to clean the filth subsonics leave behind.

On my current build, I'm going with the handguard right up against the can with a handstop to help avoid grabbing a hot can.

My opinion is that never is a good time to post anything on Twitter.

I'll look at other's ideas all day long, though.

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Trending in a good way or a bad way?

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Well, it's AR-15s and TWITTER.