Thumper2

Looks like I have it taken care of guys. I appreciate all the shared knowledge. I am new to the gas gun world and have learned quite a lot over the past couple weeks. Here is what I did. I took survivalshops and washguys advice and started looking at gas port sizes. Drilled mine to .093. Might not have needed it but purchased a JP Silent Capture Spring buffer and installed it. Went to the range and started adjusting my gas block with i round at a time. Before this it had never locked the BCG back when empty. About 5 shots at a half turn adjustment each time, it locked back. Big Smile. Loaded 2 rounds in the mag. It didn't pick up the next round. 1/4 turns at this point, 3 shots later, it fired 2 rounds. Another Big Smile. 1/2 turn more and locked it down. I loaded 10 rounds in a magazine and the fifth one misfired. Looked at the primer and it barely had a firing pin mark, but it was there. Cycled another round and shot 3 more times and the same thing happened. Odd. I pulled the upper and lower apart and looked at the JP pc. It was a little ways back from the buffer spring retainer pin, shook it and it was loose. Pulled it out and put 2 quarters behind it and fired 4 magazines with no misfires or mishaps. Came home and cut a pc of the nylon bushing they send with it .125 and dropped it in, put it all back together and Guys...I think I'm done. Now to start working up loads. Thanks again guys for all the shared knowledge. If anybody ever needs AC advice, hit me up.

I can pull the BCG out of battery about an inch and with the muzzle pointed down it goes all the way into battery when dropped. That's not an issue. It ejects, from what I can tell, at about a 4 oclock angle. Believe it or not it only picked up the next round with the Winchester 7.62X51 ammo, but only a few times. I tried adjusting the gas block with that ammo and never it cycled right, and never on the 155 AMAX, not even once. The charge handle comes past the bolt catch right at 3/16ths. Manually, I can strip 25 rounds out of a magazine, no issues, so I don't think travel length is the issue. Everything lines up, the gas tube is the correct length, gas block is orientated correctly. Do you happen to know what size hole the gas port in the barrel is supposed to be? Can you drill the hole bigger if it's under gassed? or what is the solution for an under gassed gun? A softer spring on the buffer?

The spring is 11" long. I bought the upper receiver, BCG, and barrel as separate pcs.

Spring is 27 coils from end to end, buffer is 2 1/2 inches long. I don't have a scale that will weigh it though. It will lock back manually with an empty magazine in it. It has only loaded the next round a half a dozen times at most but never more than twice in a row. As far as the bolt catch goes, it's pretty smooth. That's a really close up pic with a lot of light.

Looks like the exact buffer tube and spring that's in it.

I'm not sure what brand lower parts kit it was. We put everything together at the shop where I bought all the parts.

Couldn't get in the forum by my original login password. So here I am as 2. I've got about 50 rounds shot so far, with the malfunction I haven't spent much time at the range with it. Let me clarify something. It has never locked the bolt back after the last round, however, it has picked up the next round about 5-6 times, but never more that twice in a row. I can pull the BCG out from battery about an inch and drop it and it goes into battery no issues. It's lubed well, no issues there. Bolt catch image below.