300 blackout ammo problems

[downthefence]

ok so I decided to dive in the 300 blackout pool. I bought a sota arms upper which looks to be very nice build. it came with 150 rounds of ammo. so when I tried to shoot it only about one in five rounds would camber and fire the other 20% would lock the upper up.
what do I need to be looking for in the ammo to show me the problem

 

[JBKnifeworks]

Lock the upper up how? partially chamber the round? Start with the ammo. Try some different ammo to eliminate that possibility. Next I would look at your mags. Then the chamber.

 

[redirt78]

Dirty chamber, gas block not lined up properly, gas key out of line or not seated and torqued properly, bad gas tube alignment, loose gas tube in gas block, bent gas tube, not enough lube on carrier, wrong buffer spring, wrong buffer... Have you ran this lower on other AR's? Have you tried swapping either the bolt or carrier from another rifle or possibly both? How exactly is it "locking up"?

 

[redirt78]

Also forgot to ask if its a name brand ammo. I have had intermittent problems before with the cheap white and green box Remington but it's good for getting a decent zero on a red dot or scope before switching to better ammo

 

[T-Roy]

Need more details on whats happening when it doesnt work correctly.

 

[redirt78]

Does the barrel have M4 feed ramps and do they match up reasonably well the the receivers ramps (if it has them) if one has the cutouts and the other does not or if they don't mate up smoothly that can cause feeding problems. How does your spent brass look? Are the primers swollen, pierced or blown out of the brass all together? How about magazine choice? I've always had good results with Pmags

 

[dunkel]

Are they reloads? Hand formed brass?

 

[downthefence]

the ammo does not have any name on the bags and is a mix of different brass
the bolt locks up and has to be pryed back when it does not chamber a round
I went through a bag of the ammo just to see what would camber maunnally and easily extract and found 12 rounds out of 50 would not chamber would yall think that there was just something off in the manufatering of this ammo

 

[Patryn]

the ammo does not have any name on the bags and is a mix of different brass
the bolt locks up and has to be pryed back when it does not chamber a round
I went through a bag of the ammo just to see what would camber maunnally and easily extract and found 12 rounds out of 50 would not chamber would yall think that there was just something off in the manufatering of this ammo

I dont shoot no name .300 or GUNN ammo.

 

[northgeorgia30143]

You should double check cartridge dimensions if you have calipers and eliminate that first. I would play it safe and just throw them out or rework them.