Published chronograph velocity data for a 5.5 inch Remington 1858 revolver.
Powder by Volume-------Bullet Weight ------ Average Velocity
28 grains 3F Pyrodex----138 grain 451 ball----593 ft/s
32 grains 3F Pyrodex----138 grain 451 ball----700 ft/s
32 grains 3F Pyrodex----140 grain.454 ball----850 ft/s
35 grains 3F Pyrodex----138 grain 451 ball----875 ft/s
35 grains 3F Pyrodex----140 grain 454 ball----945 ft/s
35 grains 3F Pyrodex----143 grain 457 ball----960 ft/s
37 grains 3F Pyrodex----138 grain 451 ball----950 ft/s
37 grains 3F Pyrodex----143 grain 457 ball----960 ft/s
42 grains 3F Pyrodex----143 grain 457 ball----1019 ft/s
46 grains 3F Pyrodex----143 grain 457 ball----1050 ft/s
37 grains 3F GOEX BP--140 grain 454 ball----898 ft/s
40 grains 3F GOEX BP--140 grain 454 ball----949 ft/s
42 grains 3F GOEX BP--140 grain 454 ball----964 ft/s
Source:
http://poconoshooting.com/blackpowderballistics.html