Whats wrong?

[gober13]

I have a PSA upper/lower that is doing something similar, and it has well <500 rounds through it. I'm in the process of sending it back to them (PSA) to be serviced/repaired. Not sure if it is an out of spec FCG or bolt/firing pin issue.

What with the bolt/firing pin would caise that? Mine is a troy upper and semi auto bcg.

 

[HydroAuto]

My thought was that either the firing pin channel is crudded up and keeping the firing pin in a forward position making it basically an open bolt machine gun, but I've thoroughly cleaned it and basically disproven that theory. My other theory is that the inertia of the firing pin when the bolt slaps forward is making it move forward enough to smack the primer. I believe pistol rounds have 'softer' primers, and pistol ARs (mine is an AR9) don't have a light spring to hold the firing back except for hammer strikes. But again, I don't know, it could just be a trigger part that's out of spec. Just guesses on my part though.

 

[jcountry]

If the disconnector spring is cone shaped, it is installed upside down. That can cause the double taps.

 

[Allsmiles]

One other possibility is that you have a 7.62x39 firing pin in the bolt. They are a little longer on the primer striking side. They are normally "enhanced" by machining the first flat shoulder a 1000th or so they extend into the bolt farther. Try a different firing pin if you have one and see if it still happens. This might allow the FP to make contact with the primer when the bolt is closing sometimes. I would start by checking/swapping each and every part of the FCG for issues until nothing is left.

 

[HydroAuto]

I have a PSA upper/lower that is doing something similar, and it has well <500 rounds through it. I'm in the process of sending it back to them (PSA) to be serviced/repaired. Not sure if it is an out of spec FCG or bolt/firing pin issue.

Finally got mine back from PSA, they sent a letter apologizing and stating that they found something wrong with their FCG and replaced it.