i recently bought a yugo sks 59/69 a1,I took it to the range and it would not cycle and kept jamming.itook it all apary and the gas valve was badly pitted.iput a new murray chrome valve now it shoots great my question is ,do you think that was from corrsive ammo also there is a very tiny pit in the gas tube through to outside .inside the barrel seems to look good but i'm not sure if i know what to look for.i see no pits with a light.when i got the rifle the barrel was extremely dirty with spent gunpowder blast.alot of ranges won't let you shoot cheap russian ammo that's magnetic meaning steal bullets. why do thet make corrosive ammo.if you can't clean quickly it could cause damage.i'm somewhat new to these type weapons. thank you.