Well, my day at teh range SUCKED big time.
I went out to troubleshoot a FTE problem, switching from surplus ammo (GSS slightly dented mixed headstamp) to IMI M855 to see if the ammo was causing the FTE's.
Well, I had 2 doubles, and a few failures to go into battery. The bolt would stop halfway over the mag, after fully stripping off around. So I bought a box of PMC to see if the IMI was the cause of THOSE 2 problems. So I loaded 10 rounds on top of 2 IMI rounds. Fist 2 shots no problem, and then I had a  3 round BURST!!!!
So I talked to the RO, who is into comp shooting, and he gave me a few things to check.
I get home, and read the TS primer here, and d/l the manul from the old site.
I go over the upper and see no problems, and then go to the lower. real visible wear in the FCG either. So I slap the CAR back together and decide to try hand cycling the bolt and letting it slam home.
Well, I got the hammer to NOT EXACTLY follow, but lets just say that even a tiny amount of pressure on the trigger after it resets will drop the hammer.
THe bump fire guys would be impressed, but I don't thoink that anyone wlse would.
Time to replace the hammer, at the very least!! And round file any parts that I replace!!

I wish I had problems like 3-round bursts.

Quoted: I wish I had problems like 3-round bursts.

No you don't.  The problem he is describing sounds alot like a slam fire.  Very dangerous!!  The hammer follows the bolt carrier home and fires before the bolt is properly closed.  In a short time his gun will probably Kboom.

Sgtar15

No you don't. The problem he is describing sounds alot like a slam fire. Very dangerous!! The hammer follows the bolt carrier home and fires before the bolt is properly closed. In a short time his gun will probably Kboom.

What might cause his gun to do that?  And would a gunsmith be able to fix it or is the gun toast?

How can it slam fire when it is impossible for the firing pin to contact the primer before the bolt has rotated fully closed?

At that point it is NOT out of battery.

Most likely he is bump firing (inadvertently) because the sear surface has been screwed with or is rounded off.

Change out the hammer and the trigger while you are in there.

(I really must learn to use spell check before posting my thoughts)

Quoted: In a short time his gun will probably Kboom. Sgtar15

Nah.. Won't kaboom. 'Cuz I'm not gonna shoot it until I fix the problem!!!

Quoted: Quoted: In a short time his gun will probably Kboom. Sgtar15 Nah.. Won't kaboom. 'Cuz I'm not gonna shoot it until I fix the problem!!!

Good idea.  I agree that if you replace the hammer and trigger the problem will probably go away.  Hell, I am positive of it.

Sgtar15

Right.  The firing pin can't touch the primer unless the bolt is locked.  You'd best just replace the whole trigger mechanism with a high quality set.  Be careful of the stuff you find at the gun shows.

I wish I had problems like a selectable three-round burst...Mmmmmm....Three-round burst...