Mike H,
Thanks. The brass darkening is accomplished per Jim Kibler's recommendations using a "brass ager" solution sold by a company called Historic House Parts (
http://www.historichouseparts.com/pdshop/shop/category.aspx?catid=107). I usually finish the brass parts to a 600 grit or so, do the engraving, and blacken the engraving itself with brass black from Birchwood Casey. I then buff off the surface with 1500 or 2000 grit paper that just takes the black off the surface but leaves the engraving dark. This also removes any very slight burrs that are left from the engraving. Then I clean the parts with acetone and rub the brass darkening solution on the part with a cotton ball or piece of folded cheese cloth. I try not to get it overly dark to start with and rubbing on the solution slows the process. Usually, you are supposed to immerse the part completely until the desired color is achieved, but this leaves it uniformly colored which doesn't look right. To me, there should be worn areas that are brighter and other areas that are darker. The process of rubbing on the solution also leaves the surface a little blotchy which variegates the overall coloring. To blend it all, I use Taylor's trick of swiping the surfaces, all in one direction, with fine (0000) steel wool. If I overdo the rub down, I just darken again until it looks right.
I did a very quick job on these parts to get a sense of how they will eventually look. I won't do the final finishing until I'm ready to assemble the rifle for the final time.
