My buddy just received his DPMS AR in 7.62x39 that he had ordered eight mos ago.  After the long wait, he was pretty anxious to take it to the range but was pretty disappointed the first time he pulled the trigger.  He was shooting Golden Tiger and Wolf steel case ammo and the first shot failed to fire and found a light strike on the primer.  He got light strikes and failure to fire on several more rounds with the slightly less from the Wolf.  He also has a Mini 30 that never missed a beat with the same batch of ammo.  The primers of the rounds that did not go bang all showed light strikes and the ones that did looked light too,

I dropped his lower to check the hammer/springs and found everything to be in line.  I then popped the bolt and did not find any problems there with firing pin moving freely.   His firing pin appeared to protrude from the bolt face about as much as on my 556 AR so don't think there was a problem there either.

I then took a look at his ammo but want to restate that the same ammo fired in his Mini 30 perfectly.  What I did notice was that the primers on both looked to be seated deep, with the Golden Tiger deeper.  Others at our range with AR's chambered for 7.62 are not having problems with this same ammo his AR is.

Anybody has suggestions or experiencing the same problems with these imported steel cased ammo?  He did try pushing on the forward assist before pulling the trigger but that did not seem to help.  The distributor says that it's the fault of the ammo and that he should only use US made ammo but he ordered this 7.62 because he wants to shoot cheaper imported ammo...

The first thing I checked was the hammer spring.  Even though it was brand new, factory assembled, I wanted to confirm that it was put together right.  It was and pulling the trigger and catching the hammer with my finger, it "felt" adequate.  As for the firing pin protrusion, it looked like it was about what my 223 AR was but maybe a little on the low side of the tolerance.  Who can he see to get the fp stop modified?  Or do they sell different dimension fp's?

Thanks for the input!

––––––––––––––––––––––––––––––––––––––
1)Check your local yellow pages for a gunsmith, explain you want the firing pin protrusion set at .037-.039 as listed above.

2)Ship the entire rifle back to DPMS and ask them to fix it.

3)Take a fine file and shorten the tail of your bolt a few thousands of an inch to get the correct protrusion.

One of these is the less expensive route (#3) the others are if you are unsure about working on the rifle.
––––––––––––––––––––––––––––––––––––––
Seriously, a good gunsmith can correct this issue quickly and ensure it goes bang every time.

Now that you all posted some info I knew what to search for and found a bunch of info.  It looks like there are special fp's or bolts for 762x39 ammo and even ways to mod the fp to protrude more.  I thank you all for your input.

Owner has a lathe and sent him several links to this subject.  He has ordered a couple of fp's and will probably modify the replacements.  He did not want to modify the original...just in case he needs to return the AR for warranty I guess.  

Thanks!

you are better off modifying a $15 firing pin than a $60 bolt for sure

Wouldn't a orange heavy hammer spring solve it quick, and easy? Seems to work great on 5.45x39 milsurp, with a standard fp.


edit: ps sorry I didn't mean to quote you, I meant to hit reply.

Well he chucked the fp in his lathe, trimmed 0.07 off the stop flange and it's been all good.  Nice dent in the primers now.  Now he has another problem but will start a new thread...

Thanks for the help!