took the 7.62 to the range today to dial in the new sights.  it shot beautifully......but only on winchester ammo.   i had some f the cheaper golden tiger stuff from my sks bullpup and it would not shot off even one roud of it.  i compared the lengthe of the shells and the posititon and depth of the primer strikes between the 2 rounds and everything seems the same.  should i possibly change the firing pin spring to a lighter one so the pin comes out further.  btw....its a colt 7.62x39 upper and a colt bcg and everything fed perfectly and ejected perfectly

How much firing pin protrusion do you have? Alot of times the 7.62x39's don't have enough firing pin protrusion for the surplus and russian ammo. They might also need struck a little harder, I have a heavy hammer spring for my build. (I haven't finished mine it still needs a BCG - but I purchased the heavy hammer spring in advance)

Some ammo is way undersized so the ejector push the case to the front of the chamber and the FP does not strike deep enough. Some has a recessed primer which causes the same problem.
Winchester is good 7.62x39 ammo, the old Wolf seemed to shoot well and just as fast as the Winchester. Rem is usually slower, the corrosive stuff is pretty bad about being undersized.

Model 1 Sales enhanced 7.62x39 firing pin.
 

This is probably a good plan. Its kind of odd when you fix a colt with M1S parts, lol.

 

The M1S pin is the only way I've found to have a reliable x39 setup.

Stronger hammer springs don't mean the firing pin will reach the primer for reliable ignition.

Carry on.

+1. I did the fp mod. No neef for the ctra pwr spring after that. Xtra pwr spring=super heavy trigger pull.

this, then use normal parts



 

Same here last week.  about 7% ftf on my new build.  Got the wolff xp hammer spring with the lighter trigger spring so pull was a wash (wolff xp recommended by the others here) and today only 1 out of 100 ftf  but I was letting a guy shoot it and think chambered it like his grandma.  Have about 0.035 pin protrusion.  Very much liking this build.  My poor 5.56 is starting to be neglected and it has all the neat shit on it.  May have to take the eotech off and see how the commie shoots with it.

Yep. Chuck the FP in a drilll and take .007 off of the front firing pin collar with file or stone. Doesn't have to be pretty.

OK, ""back in the day"" before industry started to listen some!!!   Hone rear of bolt to get .045 protrusion and this was max then pin shoulders  bottomed against front of bolt,this procedure lets you use any Mil-Spec firing pin and only the bolt and barrel are dedicated,  then do the opposite of the (15 minute trigger job) and bend the legs of the hammer spring  forward to get more hammer stike.  My 762x39 has ER Shaw barrel, Oly bolt, Franken Mags.  No special bought parts, but with industry supporting, why not buy them so you do not have to figure it out like some of us did.  Just shoot cases of ammo and have fun.

just oredered the enhanced firing pin from model 1....ill let u know how it works out......btw i ordered a bunch of those complete polymer lowers from jabtac, will be picking them up from my ffl tomorrow and using it on the 7.62 and my .50 beowulf........keep ya updated on that in new thread i guess

Here is Joe with a x39mm AR-15 firing Wolf Military 124 gr. FMJ Commerical Seel Cased ammo @ around 2,520 FPS (Hot),
out of a 18" bbl. using a Five round ASC mag (function testing)...Full lockback with a empty mag...

http://www.youtube.com/watch?v=BlwAxAZNFgw&feature=plcp

Dam.....enhanced firing pin came in already.....got about 500 rnds of golden tiger from my sks to feed Thru the AR.......goin to the range on Sunday......let you know how it works........also got on of those mako group gl shock, internally shock absorbed stocks that are on eBay for 100 bucks.....we will see how that feels too

http://i98.photobucket.com/albums/l270/drw7475/IMG_20120907_211534.jpg

The GL Shock stock works as advertised, it's not a gimmick in my experience.  I find it quite effective.



 

so i got out to the range today after making a few mods to the 7.62 AR, most importantly the enhanced firing pin.......didnt work as well as i hoped, it did however begin to fire the russian ammo, i had about a 60 percent fire rate, and those that didnt fire, i sent back through a second time and they went just fine.  i guess the next thing ill try is the heavier hammer spring or maybe just get the better bcg, althugh mine is a colt so it probably is a fairly good one, just likes american ammo only.

on a second note......i installed the new frontier completely polymer lower reciever and it functioned flawlessly, the mako recoil stock was absolutely incredible for absorbing the shock this thing puts out, and i put a mako vertical grip/bipod on also.....the grip is nice and fat but the bipod leaves something to be desired, it does work ok though.....also put on a cheapy ebay grip that was fat and had finger grooves and a base, perfect with the bipod and for my large hands, and a barska 4-10x50 scope that i just couldnt get dialed perfect, maybe next time when all the ammo actually fires and im not aggravated


by the way, i tried tulammo, wolf, and golden tiger, they all functioned the same......i also tried some round nose crap that came in a blue box, wouldnt even feed out of the mag

any other suggestions about this russian ammo problem would be great

yeah, you should have replaced the hammer spring as well, like multiple post have said. Or at least bent it to get more impact. Are you sure its installed correctly???



how much FP protrusion? You can sand down the tail of the bolt if you need more.



 

i just cleaned it today so i measured firing pin protrusion.  its .055 which should be more than enough to contact properly and fire off russian stuff

does anybody think the polymer hammer has anything to do with it.....maybe it flexes when it strikes????

wolff hammer spring and wolff lighter trigger spring are en route

this with no regrets, pick up the heavier hammer spring too

Probably yes, but most likely a combination of things.
With the no fires, are you getting dimpled primers ??

Yes primers are dimpled, I didn't compare them to the rounds that did fire tho......I have an aluminum lower with all steel internals I'm going to try next Friday.....in the meantime I have Wolff parts coming for the polymer lower

you have a plastic FCG??? Yes that would be a problem.



I would shitcan all of it and get at least a milspec FCG and then a wolff hammer spring. If that doesn't fix it then theres soemthing else.





BTW did you build this lower, where did you get the parts?????



 

Its the new frontier complete polymer lower.....works great on my 5.56 and my Beowulf.......just assumed it would on the 7.62.....I'm going to try my standard lower before I change anything else

I'm running a Plum Crazy lower on my 7.62x39 Alpha Shooting Sports upper, shooting Yugo surplus ammo I've had zero issues with FTF. When I first switched from my RRA lower to the poly lower I thought the lighter plastic hammer might cause problems so I ordered the enhanced firing pin, but before it came in I shot about 100 rounds including some Wolf with no light strikes. I decided to put it in anyways but I don't think it was needed.