300BlkTalk

Dr.Phil wrote:Has already been made...

Based on the shape in the pic I don't think those can be loaded to mag length and not pigeon toe the stack.

I think the 300 BLK would benefit from a purpose built mag that has the front rib at the neck/shoulder. I think it's unlikely a barrier blind subsonic bullet design can be made with a shape for optimal feeding in a 5.56 mag. That said most people don't need 300 BLK specific mags. Many standard 30 ca...

Do you have a known good carrier you can try?

Did you assemble the upper or did you buy it complete?

It is most likly the gas key. It's possible for one of the bolt heads to shear off but remain in place due to the staking. The key will not be noticeably loose but will leak enough to cause malfunctions. To check for interference with the trigger. Dry fire it, keeping the trigger held to the rear. C...

Gun weight, shooting position, how the gun is held, and caliber/recoil will all play a role with unintended bump firing. Single stage with short pull designs are much more likely to have problems than the two stage trigger design with it's long first stage. I suspect some of the very light triggers ...

I think it's cycling just fine. Load one round in the magazine and check the bolt locking back. Some light triggers are quite easy to accidentally bump fire. But it happens so fast the hammer follows the carrier forward before the bolt can lock and cannot fire the round. Try consciously pulling the ...

Handguard dimensions are usually rounded up or down a bit and are taken from the front of the upper rail, not where the barrel starts. This is why the math doesn't come out just right. You need a regular carbine length handguard and the deep socket AAC mount for a flush fit with an 8.2" barrel....

I would very much prefer 1/7 twist on a barrel that short. You also have to think about handguard options when you go under 8" of barrel.

What kind of handguard is on it?

You need to describe the malfunction better to get a better answer.

Try to use factory ammo to troubleshoot.

Check for any unusual drag in the BCG stroke. Try a known functioning BCG if you have one.