I hate using stamps, but some jobs require it. One technique i learned watching goldsmith's stamp inside ring shanks really has helped. The trick is to not try and get it all with one hard whack.
I set my punch down on the metal, right where i want it to go. I lean it ever so slightly towards me, and give it a good hit, but not too hard. Then, I keep striking the punch with my hammer, and rollit away from me, and then side to side, trying to make sure every part of the stamp gets covered. Yu can feel the stamp "index" in the first heavier marks that it has made, which gives you a way to avoid that ugly double stamp ghost effect.
I often get by with just a chasing hammer for this task. having the work well supported is absolutely necessary. The bigger the stamp, the harder this is to pull off. For larger complicated designs, maybe having two or three stamps would be easier, then you just have to line them up very well when you go to stamp each one.
Give it a try on some scrap barrel piece, and see if it works for you.
take care,
Tom