Get a heavy 2X4 maybe two feet long. You can use it to beat the bolt open when it gets sticky.
I have been told that is what the Russians did. That is what I did too with a Chinese made one. It never seemed to hurt the gun. It only did that with certain ammo, also Chinese made.
Oh noooooo..... no 2×4 beatdown. That’s a rare soft receiver with locking lug setback. Get another one.
It’s the thick laquer on the older surplus. First 5 rounds are OK, but once the chamber heats up, the round sticks in the chamber. Stay away from older laquered ammo from the ‘50’s, stick with ‘70’s Russian, Romanian, Bulgarian, Hungarian. Aimsurplus is a good source.
The Yugoslavian is brass cased and the best, but it dried up years ago.
I’ve heard bad things about the Chinese models. That’s why I wanted to go Russian.