I have two that have been working fine, but an enhanced firing pin would have been good. - Faxon Firearms 7.62x39 Bolt Carrier Group, Type

So, it seems that a lot of 7.62x39 steel cased ammunition has unreliably deeper seated primers. A regular AR-15 firing pin with this ammo may result in light primer strikes. I replaced the firing pins with enhanced firing pins, which are slightly longer, and no more light primer strikes with steel cased ammo.