Col. Batguano,
After I engrave the brass, I use Birchwood Casey's "Brass Black" to darken the cuts. It also darkens the rest of the surface, so I polish it back with 2000 grit abrasive paper before I antique the surface a little.
The engraving is all done by hand, some push, some hammer, and some with a 30 year old Gravermeister. For this rifle I only used two graver shapes, a square and a flat. Both very small.