Dan, every analysis I've either seen or commissioned for antique brass leads me to believe that old (17th/18th century) brass was basically cartridge brass (modern 260 alloy) with lead in it, up to maybe 2%, although of course the allow was never a perfect 70/30 ratio like modern stuff with "certificates." But it was typically close. When I used to run my own castings, I was using largely just straight yellow brass and I'd always add some lead to the crucibles. Frankly I could never see or feel or smell a difference in color between what I cast and what Reeves cast.
I've read some interesting writings on brass cast during the Rev War, whereupon apparently anything went (goes). I have seen some muskets that are believed to be American, made during that era, with brass that really looked kind of funky. But I've never personally seen anything like that on a rifle.
