I'm really into rocketry and the space program, so I thought this might be a good way to pay tribute to the thing that pretty much all of 70s & 80s sci fi is inspired and enable by -- the rocket engine. My first idea is to put mach diamonds like this:
down the barrel. Here's what I've got so far:
For the rest of the gun, I don't have any specifics yet, but I'm thinking of having a texture similar to the outside of the RS-25, or SSME (Space Shuttle Main Engine):