Some of the piston systems work off the shelf with 7.62X39
The Adam Arms needs some tweaking ...they are very upfront about that. I prefer the Adam system since the assembly can be taken apart and cleaned very easily. I figured it would be worth the time futzing with it
Once I figured out the optimal gas port size it runs great
Let me know if you go with the Adam system. I can save you lots of growing pains .
