Howdy

A subject near and dear to my heart. Here is a comparison of two pressure curves that were sent to be by a gentleman who used to work as a technician in a ballistics lab. The two charts are for two different shotgun loads that achieve the same velocity with the same weight of shot. The Black Powder curve is from a 3 dram charge (82 grains) of FFg Black Powder. The Smokeless curve is from 18 grains of an unknown Smokeless Powder. This chart shows the typical relationship of a Smokeless charge and a BP charge propelling identical projectiles at the same velocity. The peak pressure of the Smokeless charge is higher, and the duration is of the peak is much shorter, creating the sharp spike. It is not just the peak pressure, it is also the sharp spike that can damage an older gun with older steel, shocking the steel more than the gentler curve of BP will. What you say may be true if one works with a specific powder, but I would be much more comfortable seeing the duration of the pressure spike, in addition to the peak pressure.

I shoot a great deal of Black Powder in cartridges, I go through about 20 pounds per year. For me it is just much simpler to shoot old guns with Black Powder than to risk an old gun with Smokeless. Colt did not factory guarantee the SAA for Smokeless powder until 1900. Until that time they were not confident the steel could withstand Smokeless pressures. I doubt if S&W had access to any better steel than Colt did.

I will continue to only shoot BP in old guns, it isn't nearly as much trouble as most people think.