Quoted:
Are you sure you have the proper length/type buffer and spring for your particular receiver extension?
Disassemble the stock and look inside the receiver extension with a flash light. Does it look like the bolt carrier is making contact with the tube? A bent or misaligned receiver extension can cause those problems.
Buffer tube, spring, and buffer were all part of an A1 stock kit from Fulton armory. It is a rifle length spring and rifle weight buffer. I noticed no damage to the buffer tube after ~75 rounds of use. I'll be double checking all of those when able.
Quoted:
Does your gas piston system have an adjustment? Some of them have like 3 stages and maybe the stage you have it on won't cycle with a rifle length gas system. I'm sure the gas piston system is the issue if your sure the gas hole is lined up.
The Osprey piston is a non adjustable system. Checking the gas block is very high on my list of culprits, but because the upper still cycled on a different lower, I believe there is a separate primary issue.
Quoted:
First off we need more info.
What kind of lube are you using are you using enough also?
What ammo are you using Tula or XM193?
Could be a combination of the two not enough lube and weak ammo. These are the two simplest things to check and remedy before you go onto other causes. Usually the simplest answer is the right one.
Bolt carrier and piston are both fail zero coated. Presumably this means they do not require lubrication to function correctly. I'm not saying that the fail zero is some kind of panacea, but product as advertised does not require lube. Ammo was 115gr Silver state Armory 6.8 SPC.
Quoted:
Sounds like it needs a little more gas. Alternatively you could put a spacer in the back of your rifle extension and put a carbine spring and buffer in.
One other thought, is the hammer binding on the back of the carrier while the trigger is pulled? You can test this by clearing the rifle, pulling the trigger, and while keeping the trigger pulled charge the rifle. It should move freely to the rear without binding.
I shall test the hammer for binding and if worst comes to worst I'll try the spacer.