horrible results with mini rotary- any suggestions?

[NAC]

needing to engrave this 1.25 x 1.25 trademark into a 2.5" dia brass barrel- the quality is just horrendous. I must've tried 2 dozen practice runs in brass & aluminum- changing speeds and depths with no success at all. at this point, I'm wondering if I'm asking too much from the mini rotary- maybe the full size rotary would be more capable? i'm thinking of just milling a flat spot in the customers barrel and carving the file in flat... here's an example of how the file looks carved flat into the brass- compared to how it came out on the rotary practice pieces. shark HD500 & mini rotary & using a 60* 1/4" ZrN / ALTiBN coated carbide chamfer endmill - specifically made for engraving non-ferrous metals.