Well over a decade ago I came across a Yahoo percussion handgun group, and in it was a fellow who had really researched the power of the Civil War paper cartridge company known as Hazards who was using what they called at the time a new Pistol Powder. This fellow got his hands on original paper cartridges in .44 cal and through testing found that it contained 4F powder and was as energetic as Swiss powder. The loading then was 36 grns of powder under a 211 grn conical. That’s pretty potent stuff and would have been hugely successful had they not made the conicals pointy.
I’ve seen the numbers on various .44/.45 cal revolvers using energetic 3F powder and always felt it was more than acceptable as a hunting sidearm. Of course the idea of seeing what 4F Swiss would be like is a little intriguing if I were to have some.
Recently I was directed to a black powder calculator for Swiss powders only called P-Max. It is very interesting. What really caught my eye were the pressure maxes and the power increase when using 4F. My 5.5” Pietta NMA loves 32.5 grns it seems, and I’ve been working on a universal bullet for it and my ROA as the excess chamber space is very similar with the Ruger liking 37.5 grns. This bullet looks to be about 230-235 grns so I used 230. With 3F it’s like the old 1911 ball ammo with 850 fps and 370 ft/lbs with 14k psi. Switch that to 4F and it showed 979 fps and 489 ft/lbs with 20.7k psi. Thing is my design has a long upper driving band giving it more friction than a typical bullet you see. And my design has a huge 0.375” meplat so there’s a lot of mass in a small place.
Long story shorter, a ball I’d have no issues with regardless of powder energetics, but with a bullet things can change drastically. And a most excellent example is the 285 grn version I made for my Ruger as black powder pressures aren’t a concern whatsoever. It was loaded with 52 grns of Pyrodex P and it blew the wall of the cylinder out on that Walker.
I have looked around trying to find information as to pressure testing of these repro revolvers, but haven’t found anything more than logical speculation I believe. With that in mind I wouldn’t use Swiss 4F with this bullet once created. Goex or any other non sporting grade powder I wouldn’t have so much concern. This fellow likes to make powders faster than Swiss.