Recent content by AR 15 USER

.223/5.56/.300 But I agree a .300BO magazine and supersonic ammunition might make a difference.

I would suggest marking the upper assembly, as you can visually see the difference in a. 223 round and a .300 round. I have both rifles, and both rounds. I had to read the markings on the barrels to know which rifle it was. As far as marking magazines. I use different color mags for different...

You all didn't understand. A .300 subsonic ammunition out of a .300 barrel with a full auto lower. It fired 3 rounds then jamed. That is what my brother in law told me.

He was using the correct rounds for the correct upper assemblies.

Hans understand because he was using 300 subsonic ammunition. That is why I guess!

He tried F/A with 300 BLK, it jamed after 3 rounds in a 300 complete upper assembly. Hans he has a full auto AR15, registered and all. I gave him a 300 BLK 10.5" complete upper assy with 30 rounds of subsonic 300 AAC in a ar15 30 round magazine. I was curious if it would work with 300 AAC...

Only 3 rounds come out in full auto mode. And then it jams. I told him to shoot 5.56 with a different upper assy. No response yet.

My son in law says the 300 blk Jams after 3 rounds.