Sports trophy shops in your town usually, make plaques, engrave all kinds of things. They should be able to do it for you, or lead you to a jeweler, or as previously posted machine shop, fabricators, gunsmiths especially the old school types with the ornate, quail gun or rifle.
Lawyers would love to feast on your gun and blood lust (
with engraving, even if your totally justified in any type of SD shooting, if it's placed into evidence and through discovery the other lawyer gets to parade it around in court.
Although, I think it's kinda cool...Just sayin,.....