AR Sponsor
Posted: 1/17/2010 2:14:59 PM EDT
|
I recently switched a 7.62 x 39 Olympic Arms 16'' carbine SS upper from a LRB lower with a Rock River parts kit and a bushmaster fixed telescopic butstock (Bushmastr spring and buffer) to a Spike's Lower with a rock river parts kit and an armalite a2 buttock (armalite m15 buffer spring and buffer). I'm using a c products 10 round 7.62 x 39 magazine. The rifle fires all day long in the LRB lower eating up wolf 152gr soft points, this brass Egyptian brass berdan primed crap and this real nice prvi partizan match ammo. As soon as I put the upper on the spike's the gun fail's to fire. I take out the unfired round and its got a real deep indent in the primer. I put that same round that failed to fire back into the gun with LRB lower configuration and it fires. I don't think its the firing pin causing this. Any suggestions would be greatly appreciated. |
|
Some configurations of 7.62x39 ARs have a notoriously hard time lighting off the hard primered stuff such as Wolf. My first guess is that the critical difference between your two lowers is in the FCG, most likely the aforementioned hammer spring. I did notice that both lowers use RRA LPKs; nevertheless, that's the likely area of difference.
Assuming you're moving the BCG with the upper, it's hard to see how the firing pin would be responsible as it's the same in both arrangements |
|
The same thing happens with the 5.45x39 uppers.
With a stock lower they will shoot wolf but won't shoot russian or bulgarian. (lots of FTF). Put orange (extra heavy hammer spring) in and it will set off a rock. I have hte same problem in an SKS. Shoots wolf but FTF on Monarc (russian) ammo. The bolt and firing pin on the SKS has to be perfectly spotless to fire off anything other than wolf. |
AR Sponsor