What is the best way to simulate burn mrks from usage on a tank gun? 8}

I think there is no best way, just personal favourtie, mine is to airbrush flat black on. Do the trick every time. HTH.

Somepeople use pastels, and also looked great.

Depending on my mood, I either use powdered pastels applied witk a very soft brush or acrylic flat black applied with the airbrush

Hello airwarrior, if you're not that lucky that you have an airbrush, there's always the good-old drybrush technique. I even tried once a oil-pastel,(dark gray), and that worked out as well.
It's like the other guys said, it's something personal.

Bye for now, John.

If you don't have an AB, hold a candle next to a scrap piece of plastic ***BEWARE*** until you have a soot mark. you can pick up the soot with a brush and brush on.

thanks for all your help