I accidentally discovered an easy way to create my own gunmetal paint. I start by giving the barrel or receiver assembly a base coat of dark silver acrylic. Then I apply a heavy wash of black artist’s oil paint. You can go heavy or lighter on this paint for different effects; I usually mix 60/40 paint to thinner. Let it sit for 12-24 hours. 

Then buff with a cotton swab. The black overcoat stains and deepens the silver. The more you buff it, the more the base coat shows through.

Tip submitted by:
Dave MardonIdar-Oberstein, Germany