Don't use smokeless powder in a BP Richards conversion. Those conversions were introduced during the black powder era and were never intended to be loaded with smokeless powder. The Colt design is not strong enough because of the lack of the "top-strap" found on the Conferderate Spiller & Burr brass framed, and later Remington steel framed Army revolvers. Some of the Colts were even brass framed, and using black powder loads, over time the brass stretched and the gun would shoot out of timing. The only black powder revolver built strong enough for smokeless loads is the Ruger Old Army - and that's because it is built on the Blackhawk frame.