Most builders I know cut their name into the barrel with a graving tool. You can learn to do it in just a few hours of practice on a piece of any mild steel or brass, unless ya try to get too fancy. Just draw it out, follow the lines & take your time. If you know a builder close he can show you in 10 min how to do it, it is quite simple. Most of the ML parts venders have gravers for sale & can tell ya what one you need for this.
Stamps are usually used for trade marks & etc. I have a Birddog6 stamp from Everstamp I had made that I stamp on the barrel as a trademark, but I cut my name in with a hand graver. :thumbsup: