Black Powder Ballistics

[tsafa]

I have been shooting black powder revolvers for some time now; I recently bought a chronometer and an accurate scale and decided to do some tests. I compiled my own velocity data and did my own energy calculations. I wanted to share for two reasons. First in case there is some error in my method, people can correct me. Second, just to share the data.

The formula I am using to calculate energy is the one that came with the Chronometer book:
Velocity X Velocity X bullet weight in grains / 450240 = Energy in Ft/lbs

My goal was to compare my Remington .36 cal to my Remington .44 and see how the bullet weight vs velocity variations work out. The .36 had a 6.5 inch barrel while the .44 had a 5.5 inch barrel. Each group listed below is an average of 6 shots. I disqualified any readings that seemed unreasonably high or low. Testing was done under field conditions, not lab conditions, so powder measures may be off by a full grain either way.


Gun..................Pyrodex FFFG (vol).......Bullet weight......... Average Speed............Calculated Energy
.36 Remington.........28 grains.................80 grains.375 ball.....1015........................183 ft/lbs
.36 Rem..6.5 inch.....32 grains.................80 grains...............1275......................... 288 ft/lbs
.36 Rem................32 grains.................80 grains................1200........................ .255 ft/lbs (retested)
.36 Rem ...............35 grains.................80 grains................1250........................ .277 ft/lbs (35 gr max capacity)


.44 Rem ..5.5 inch.....28 grains .............138 gr .451 ball.........550..........................92 ft/lbs
.44 Rem.................32 grain...............138 gr .451 ball..........700.........................150 ft/lbs
.44 Rem................. 32 grain..............140 gr .454 ball..........850..........................224 ft/lbs (.454 ball has tighter seal)
.44 Rem..................35 grain...............138 gr .451 ball.........875..........................234 ft/lbs
.44 Rem..................35 grain...............140 gr .454 ball.........945...........................277 ft/lbs
.44 Rem..................35 grain...............143 gr .457 ball.........960...........................292 ft/lbs (.457 ball has tighter seal)
.44 Rem...................37 grain..............138 gr .451 ball.........950...........................276 ft/lbs
.44 Rem...................37 grain..............143 gr .457 ball..........960..........................292 ft/lbs
.44 Rem....................42 grain.............143 gr .457 ball.........1019..........................329 ft/lbs
.44 Rem....................46 grain.............143 gr .457 ball.........1050..........................350 ft/lbs
max capacity for the .44 is 50 grains but was not tested.

It became clear very quickly that for the .36 the highest energy resulted from stuffing the chamber to the max 32 grains. 35 grains represents an over-stuffing and compressing of the powder, which yielded diminishing returns. I only had one size .36 ball (.375) and it was a very tight fit that shaved a ring off the ball as it was seated.

.44 on the other hand required a fair degree of experimentation. Two things seem clear. First, big .44 chambers like to be filled with powder, otherwise there is little benefit over a .36. If you want to save on powder... just get a .36. The second lesson learned was that it is very important to have a very tight seal. I had been using .451 balls which I was able to seat with less effort. The testing shows a significant energy change between .451 and .454. Some Revolvers, have slight differently sized chambers and a .451 may be tight enough. The important thing is that you have a tight seal that allows the pressure to build up behind the ball before it starts to move. The tight seal will be evidenced by a ring of lead being shaved off when you seat the ball and significant resistance when seating.

The energy of these black powder revolvers is quite impressive. It is also worth noting that the original pistols sold by Colt and Remington did not have any instructions as far as how much grain to load into them. It is probably fair to say that soldiers and cowboys loaded them up to the max.

I did some similar tests with modern pistols and got the following results.

.38 special snub .... 158 grain MFG.................................750 ft/s...........198 ft/lbs
.38 special 6".........158 grain MFG.................................800 ft/s.............226 ft/lbs
.357 6"..............125 gr Reloaded near max with Unique.....1250ft/s............433 ft/lbs
9mm Glock 19.......115 gr...Winchester white box...............1150 ft/s..........337 ft/lbs
9mm Glock 19 .......115 gr Reloaded to max with Unique.......1190 ft/s..........361 ft/lbs (max= never exceed load)