View Full Version : BP Compression Question

October 3, 2010, 03:19 PM
If you load your revolver and compress the bp, what will be different than if you didn't? Obviously you don't want the chamber to have any air space in it so everyone compresses somewhat, but is there a right amount to compress??

October 3, 2010, 07:03 PM
777 is finicky and doesn't like to be compressed but can't have an air space. BP and the rest of the subs just try to use the same amount of pressure every time.

October 3, 2010, 10:03 PM
Boy ain't that put us in a bad place-
I have a lb of several kinds to try when I get a chance including 777
Me thinks there will always be a degree of compression when loading and it seems like some compression is better than leaving space- Right?


October 4, 2010, 06:14 AM
Yes, some compression is better than leaving an air gap. Be sure the projectile is seated, but don't give the loading lever a good hard PUSH. Firm, but don't go into bubba mode.

Too much compression with 777 is not a safety issue; it simply results in inconsistent burning, and thus inconsistent velocities. Too little compression, that is, an air gap, is a safety issue.

October 4, 2010, 08:38 AM
mykeal is right. Seat firmly but do not force compression. What you could run into is turning the powder from granules into dust and increasing pressures. But, to be realistic, in a pistol, you would not raise pressures enough to cause a safety issue. What you would do is cause an inconsistency in loading, changing velocities and POI. Whether the black powder game or modern reloading, consistency is everything for accuracy and, ultimately, safety.

October 6, 2010, 09:55 AM
If you load your revolver and compress the bp, what will be different than if you didn't?

I think that there very well might be a measurable velocity difference for some powders and granulations if a chronograph was used.
And a tight over powder card might also contribute to making a difference since it may act as a more effective gas check than the ball alone.
A loading press also tends to more easily increase the amount of compression especially if it has a longer lever, as does first directly compressing the powder before ramming the ball.

Put all three methods together, the OP card, the loading press and ramming the powder first before the ball, and that should increase the liklihood of a meaurable velocity difference.
But without a chronograph to take precise readings, then the amount of increase in feet per second (if any) would just be anybody's guess. :)