I'm not sure if anything has changed but it used to be, that the engraver did not need to have an FFL if they returned the weapon the same day as it was dropped off. My recollection is that the engraver had to be an FFL if any firearm was left overnight. That may have changed though. If you are talking laser engraving the engraver must have a cabinet big enough for a long gun and many don't. If you are talking machine engraving many engravers hesitate to use their gravers on steel. They more prefer to engrave brass plates, trophies and awards that sort of thing. I have used an FFL who just happens to have a laser engraver in Northwest Georgia I could get that info to you if you are anywhere close to there.