Ar 7.62x39 and 3 lb trigger springs

[adelbridge]

So I ordered parts for a 7.62x39 upper and it dawned on me that Russian surplus might not be compatible with my 3 lb timney trigger. Anyone have experience with shooting Russian surplus with lightened trigger springs?
The trigger stays so this upper could end up getting expensive.

 

[rbernie]

The trigger has nothing to do with being able to shoot steel cased ammo. Success with steel cased ammo comes down to chamber specs, extractor springs, and firing pin protrusion.

 

[M1key]

Model I Sales sells an "enhanced" firing pin that is slightly longer to facilitate reliable ignition.


M

 

[adelbridge]

the trigger has nothing to do with being able to shoot steel cased ammo. Success with steel cased ammo comes down to chamber specs, extractor springs, and firing pin protrusion.

I know from experience that Russian surplus primers require a harder strike. Timney make an Ar-10 specific trigger that is dimensionally the same as their ar-15 trigger, the difference is a 4lb spring to account for the larger rifle primer.
M1key thanks for the info, you may have saved me from buying a new lower.

 

[rbernie]

I know from experience that Russian surplus primers require a harder strike. Timney make an Ar-10 specific trigger that is dimensionally the same as their ar-15 trigger, the difference is a 4lb spring to account for the larger rifle primer.

The issue really isn't the hammer spring, per se - it's the amount of protrusion that the firing pin gives you from the bolt face that really dictates success or failure. A heavier hammer spring may mask the symptom a bit, but the root cause is the primer depth on steel cased ammo (deeper than 'normal') and the subsequent need for more firing pin protrusion.

The M1S firing pin has a thinner stop collar to give extra protrusion. Some 7.62x39 bolts are made with fractionally shorter tails to give the same effective result.

 

[brettboat]

You guess can still find russian surplus? I haven't seen that **** since I was like 5 years old with my dad.

Pretty sure y'all are talking about modern production ammunition and not the russian surplus that we could get at every gun show once the wall fell. Anyways, yea... Russian ammo has hard primers. May need to put the orig. spring back in and get an actual trigger job.