I use the motor
I tried to use the diamond and just could never get the results I wanted, so I learned to use the motorized spindle with a (Quarter Round ) carbide cutter and it does just exactly what I want it to do. I usually cut the letters between .003 and .010 deep and have no trouble with the round letters or numbers, the only problem that I have had is that sometimes I do get a small burr raised on the edges of the letters but is no problem to burnish off with a final polish. I do have to resharpen the point about every 8 to 10 barrels but I do that by hand on a diamond wheel I have for sharpening my carbide lathe tools.
These tools can be purchased from (Graveograph) but do cost about $45.00 each check there catalog online on page 99 for 1/8" or 104 fir 1/4" but the image on page 99 is not the right image of a quarter round tool as they have it mistaken for the parallel tool, these are made especially for stainless steels or other hard materials and do work unlike the half ground tools.