Phil Spangenberger wrote about this:
"Many SAA shooters also think the term “black powder frame” means one can only fire black powder ammunition in this handgun, and the “smokeless frame” is for use with smokeless ammo. WRONG! With currently produced 1873 SAA Colts or modern replicas of the ’73 Peacemaker, you can fire either black powder or smokeless ammo in either frame style. These frame designations tell which era a particular single action represents. However, if you are working with a vintage Colt SAA, revolvers with serial numbers under 180,000 should only be loaded with black powder cartridges-and then only after having them carefully inspected by a competent gunsmith."
I found a copy of his article here: https://www.richardbealblog.com/black-powder-framed-peacemaker%E2%80%93-what-does-it-mean/
