You can definitely shoot all the smokeless you want in the 1885 Browning! The 1-18" twist will shoot better with heavy bullets, than with light, but even 300-360 grain bullets wont shoot badly. I have the same twist in my Ballard, and it shoots the heavy bullets great, but I still get groups under 3" at 100 yds, with 300 gr cast lead bullets. My loadings are about 1200 fps at the muzzle, with smokeless powders.