Jim may be right. It's also possible the gun is a totally brown patina like the wallhangar that someone gave me, a pattern may not be visible anywhere.

There may be a way to test a small area with a single chemical to determine if its damascus, but I don't recall. I do know that the circuit board etch is used after rusting during the refinishing process to remove bluing/browning, on just the steel and leave it on the iron, to reveal a pattern.