To your question on the surplus ammo, yes most of the surplus ammo is corrosive. However if you clean it right it's not a problem.
I have several milsurps and that's all I shoot out of them:
FYI - My Polish M44 is second from the left
Normally I bring a small bottle of windex out to the range. After I'm done shooting (and before I pack up) I spray a bunch of it down the barrel and run a patch or two (also soaked with windex) down the barrel. I plug the barrel (so the windex doesn't go all over the place) and head home. Once I clean it generously with Hoppe's # 9, let sit over night, then clean/oil it completely the next day or soon there after. Excessive? Probably but I've NEVER had a problem with surplus ammo.