Here's a good site to see some nice firearm engraving.
http://fega.com/photos/
I work at a company that makes currency sorting equipment and I get to look at alot of currency from around the world. I have often wondered how many top notch engravers there are in the world. I would not suprize me that some good engraver out there has done the currency plates for more than one country.
I guess if your a good engraver there are really only a few options, engrave guns, jewelery, or currency plates. Maybe currency engravers do guns in their spare time.