[Phil Coggan]

Ron,
Copper is not a problem, as you know it's a lot softer than red and you can fill small areas in with wire.
The only thing you have to be carefull with is, after hardening, it's usually bright but sometimes it has some oxyidation, it's easily removed but if the gun is coloured it can be a bit tricky.
You also have to de-grease the gun before laquering, I usually wash it over with thinners or acitone.

Phil