.223 Feed issues

[golfer]

I know it's not a 6.5g, but I figured this helpful group could lend some insight on a .223 as well. A neighbor and I assembled a .223 kit with a finished 80%. When shooting it, the bolt ejects the empty and closes completely but does not grab the next round when closing. Each new round had to be manually chambered. None of the bullets were scratched so I'm not sure if the ramps are misaligned. We also tried 3 different magazines with the same results.

Thanks in advance from an AR newbie.

[204 AR]

Sounds like undergassed. Did you put the upper together, and if so are you sure the gas block is lined up with gas port in the barrel? If so, check the bolt carrier for a loose key. If that's fine check how much the carrier drags on the hammer when it's pulled back. I've had that be the problem before. Is the buffer spring correct for the type of buffer tube you have? If it all came together, it should be ok.

What configuration is the barrel? 18" rifle length gas by any chance?

Also what ammo, I'm assuming factory? Good ammo? Handloads? I've had certain fast burning powders give me a bit of trouble. Lots of things it could be, more info is needed.

[Popeye212]

What 204 said had similar problems turned out to to be the BCG. load one round put an empty mag in it. Fire it if the bolt does not lock back you are under gassed also how does the round eject consult this chart.

https://c1.staticflickr.com/1/647/22671928017_8c68eccc92_b.jpg

[golfer]

It is a 18" mid or carbine gas system. Sorry, I do not have it in front of me at the moment. The bolt is lacking back on the last round so it seems to be getting enough gas.

Carbine buffer.

The upper came assembled and no mixing of parts. It was assembled with the parts that came with it.

He was shooting PMC ammo.

[VASCAR2]

If the ammo was PMC Gold it is very lightly loaded 55 grain 223 ammo. PMC also sells X-Tac 55 grain M-193 and 62 grain M-855 which are loaded to 5.56 spec.

I suspect if you were shooting the PMC Gold in a brand new upper it might not have enough gas to pickup the top round out of the mag. I suggest you liberally lube the bcg then load three rounds in the mag. If the rifle will function with two or three rounds I’d suspect under powered ammo. When a 5.56/223 AR-15 has a loaded mag it puts upward pressure on the bottom of the bolt carrier, more rounds in the mag add more drag on the bottom of the bolt carrier. The added drag requires more momentum/more gas pressure to cycle.

I’d buy some factory 5.56 M-193 and see if the rifle functions. As the rifle wears in it should start cycling with the weaker ammo.

If the rifle won’t cycle with M-193 then I’d suspect the gas block is not properly aligned or the gas port is to small. Carbine length gas AR-15’s generally have plenty of gas pressure. Midlength gas AR-15’s have a little more dwell time and tend to have a smoother recoil impulse.

[Popeye212]

Pick up a box of Hornady Black the ones I bought in the Grendel were definitely loaded heavy (ie. flat primers). Should eliminate the gas variable.

[StoneHendge]

Is the bolt locking all the way back like this?

IMG_20180616_194328-486x648.jpg

Or is the bolt catch locking the carrier and not he bolt like this

IMG_20180616_194401-648x486.jpg

[bj139]

Is the magazine inserted completely?
I often have to whack the bottom of the magazine to get it to seat completely especially when a full magazine is hitting the bottom of the BCG