[ribbonstone2]

A friend has several French revolvers marked 1873 St.Entienne..they were orginally a 11 mm.With a very small amount of boreing, He has bored them out to 45 cal.He has slugged the barrel to confirm the cal.
Problem is they were orginally black powder. What smokless
powder will approximate the pressures of a 45 cal 45 cal.
What powder to use and source of supply?

Been some work done on black powder vs. smokless powder in the way they develop pressure...even at the same peak pressure, there seems to be a difference.

Not saying other people haven't used smokeless in thse old big bore revolvers and gotten away with it, but it just seems a waste to have done some much work and then subject it to loads/powders it was not designed for.