Mike -
That's a beauty too! Probably won't get banned as fast as other guns either - though to Chuck Schumer, I'm sure that looks like an evil assault handgun!
From "The Gun Digest 'Black Powder Loading Manual'", by Sam Fadala (1982), here are the recommended loadings for a Navy Arms "Harper's Ferry 1855" .58-caliber percussion pistol (I don't think the ignition system being a flintlock will matter):
Projectile: .575" 500-grain Lyman minie (mould # 575213)
30 grains FFg; muzzle velocity 577 fps; 388 ft-lbs muzzle energy
40 grains FFg; muzzle velocity 657 fps; 503 ft-lbs muzzle energy
50 grains FFg; muzzle velocity 730 fps; 621 ft-lbs muzzle energy
60 grains FFg; muzzle velocity 802 fos; 750 ft-lbs muzzle energy
The maximum recommended loading was 60 grains, but this was also the recommended hunting load. He notes that this is a powerful pistol. He also mentioned that though the mould states it was 500-grain, the projectile weighed 525 grains. I am assuming he used pure lead, but it doesn't state if he did or not.
Post a range report when you can!
![Very Happy :D](./images/smilies/icon_biggrin.gif)