What colors do you suggest I paint the breach of my pak 40 I'm talking about teh metal part that holds the round and the top "sliders" which the instructions tell me to paint silver. I hope that's clear. i was going to paint it mettalized steel.

A good color would be pencil lead color Graphite

The breech I would color with either "grimy black" (a color by Testors Model Masters), or German shwarzgrau, and then similar to SGstreet, I would rub graphite on edges, etc. to give a metalic sheen. The internal part of fhe recoil cylinders would be bright silver, similar to the equivalent part on a vehicles shock absorber.