I came across one of these recently and bought it on a whim. From what I've gathered with respect to the Texas gun laws, they don't apply to the muzzleloaders / blackpowder / antique replica type of guns like this. For example, the 30.06 and 30.07 signs are only for people carrying under authority of a CHL/LTC and the same goes with our 51% signs for bars.
Don't have a mold for it yet though, so will probably just use a round ball that I use for .38 / .357 and tap it slightly with the arbor press to increase the diameter. Either that or a 105 gr 0.358" bullet similarly widened.
First test was with just a percussion cap on it and the cap pretty much gets shredded. They definitely do not stay together like you see with normal centerfire primers. Is this how that always end up?
Second test was with a couple of grains of Alliant Promo with a 1" square of paper towel on top of it to hole the powder in place. I am well aware of the disclaimers about using smokeless powder in a blackpowder gun, but I'm curious to see what can be done safely and intend to pursue this a bit. I am using a rig to remotely fire the weapon and there is concrete filled cinderblock wall between me and the gun. If it blows up, I'm not concerned from a safety aspect. I'm also only doing a single chamber at a time, so in the event of a catastrophic failure, the other chambers will not be firing.
With respect to a holster though, I have found that the belt slide holster that I use for my M1911 fits it very well and it makes for a very concealable rig. The cylinder fits right through the opening in the bottom of the belt slide holster and is just snug enough that it would probably not fall out even if you were completely inverted.
I'm pretty sure that there are some safe smokeless loads that can be used in blackpowder guns. All you have to do is look in the smokeless reloading manuals and find ones with pressure as low as would be generated if you were using blackpowder. Of course, you also need to ensure that you seat the bullet to the correct depth since if you seat it all the way down to the top of the powder, you're probably going to end up with an overpressure situation. From the Lyman Black Powder Handbook, 2nd Edition, blackpowder pressures can vary from 13,500 to 23,400 psi, so choosing a smokeless load that is that low should be safe. Of course, start low and work your way up, just like when you are trying to develop a load for a new powder that does not have any data for your particular caliber. Starting with .38 special loadings might be a good choice. For example, Hodgdon shows that for a 90 gr LRNFP seated to and OAL of 1.325", 2.5 gr of Clays will give you 705 fps and 7900 psi and 3.0 gr will give you 938 fps and 11,400 psi. Considering the fact that the .36 chamber is slightly wider than the .38 special, the pressure will be slightly reduced from those values.
Now, what would be really nice is if Pietta would make nipples for the Pepperbox (and their other handguns) that could take either 209 or small/large pistol primers so that they would stay intact after firing. Combine this with making the Pepperbox chambers so that it could handle .357 magnum pressures and you would have an impressive gun that would avoid all the ATF rules. To reduce the chance that someone might load a bullet too deeply and thus increase the chamber pressure, they could make the chamber "stepped" (i.e. the part where the powder normally sits would be a smaller diameter than the part where the projectile sits). Kind of the opposite of a bottlenose cartridge chamber.
