I recently built a upper, it's a BCA right hand side charging bcg upper assembly with 20" 223 wylde barrel with a 750gas block, it's what the barrel calls for and a rifle length gas tube. All new parts. Barrel nut and hand guard is a ar stoner and a silencerco flash hider. If that stuff matters. The lower is psa lower off of my other ar, thats is a 16" carbine. So when I shot the bcg only goes back about a inch and that's it. Again all new stuff. Except the lower. I have read some stuff online but looking to get more specific to what's happening to mine thanks in advance

Dupe

Can you manually pull the charging handle all the way to the rear, does the BCG go all the way to the rear?  The face of the bolt should stop right before going past the rear of the ejection port, about 1/8" to 1/4".  If so, I would check gas block alignment next.

Yes I can pull it all the way back by hand after ever shot. The barrel has the alignment dimple on the bottom so thinking it's aligned correctly. Took the block off with the tube still in and blew threw it and heard and felt the air come out so the tube and block are correctly connected.

With the gas block removed, look at the gas port hole.  Is there a fulll 360 degree carbon ring around that gas port hole?  If you can post a pic.

Ok so I found the the bcg was really hard to pull back to took the bolt out and it was very dry and crusty. So I cleaned and put oil all over and now everything is moving smooth. Next step it to fire it. Will keep you updated  thank you