Dave,
You do mighty fine scratchin'
Please show us more.
Etching will work on many metals, but the etched lines and figures will not be as sharp and well defined as engraving.
If somebody makes a fine rifle, and then wants some engraving, it is a wise move to get a person like Dave, to do this work, which will enhance the quality of the gun, rather than screwing it up.
Best regards
Old Ford