The other day, we pretty well established that Dragoons are neat.
Here are some loads I've gathered over time. The H777 load, I clocked today as well as the loads below using Pyrodex Rifle/Shotgun. Note the variabity in performance. Sometimes the difference between a .457 ball and a .454 is significant-(other times, not). I had two cans of Pyrodex RS- one new and one at least ten years old that had been almost used up. I noted the same loss of velocity once when I compaired 25 year old Pyrodex P with a new can of the stuff. Interstingly enough, the old Pyrodex P hadden't lost any more velocity (relatively) than the old but much newer Pyrodex RS. Both retain the usual low extreme spreads.
I was careful to seat ball over the H777 just deep enough to dent the top of the powder column without compressing it very much. This seems to be the key in getting consistent velocities with that stuff- though I'm still far short of really understanding it.
