Difference between Nickel amd Copper coated fmj ammo?

nickle is harder than copper. Next to no extra fouling. HOWEVER, surplus ammo, unless USA, is normally corrosive powders and primers. Plus, the bulk of non US mil-surp is berden primed. A pain to reload. On the plus side? Mil-surp ammo is normally more powerful than today's modern. So, an older pistol will fire like it's suppose to.

Strictly a balance. If, the 32 surplus is in good condition? You will do fine using it. Newer pistols mostly have stainless steel barrels. So, hard nickle vs copper near a non issue. Just clean pistol completely after using mil-surp ammo. Try some and you'll like it. Compare recoil and accuracy over today's commercial stuff.

Everyone says copper is horrible to foul but i shoot 800 to 900 yards with a rem 700 vtr 308. and i run a bore snake every 5 rounds and dont have any problem with fouling. if u let it go 20 and up it gets rough but other than that i love my copper fmj. but the nickel i couldn't tell u

Nickel is very hard. I doubt what you saw was nickel-plated. It was probably cupro-nickel, which wasn't as satisfactory an alloy as gilding metal, which is about 95% copper and 5% zinc, but was pretty decent in its day.