Slow ball ballistics

[Canuck Bob]

Slow ball ballistics interests me.  I want to shoot slow ball loads in my .54.  1000 fps or less is my velocity range.

I've been studying subsonic ballistics and decided to do some research as it pertains to round ball muzzleloaders.  I started with Lymans current manual.  On page 226 Lyman lists loads for round balls and 2F Elephant.

40 gr  1059 @ muzzle  837 @ 100 yds.

To gain 100 fps at 100 yards 70 gr charge and 300 fps extra are required at the muzzle.

70 gr  1354 @ muzzle  939 @ 100 yds.

To gain another 100 fps at 100 yards over 120 gr of powder would be required and an additional 300 fps at the muzzle.

120 gr  1623 @ muzzle  1025 @ 100 yds.

The return to the shooter is neglidgeable at 100 yards.

[Canuck Bob]

Sorry for second post, the post function acted up.

The most amazing thing is that the lowest load produces the least wind drift! 

I aplied this thinking to a ballistic calculator on the web and was surprised at the little difference an extra 600 fps makes after 50 yards.  The wind drift results floored me.  I've never studied ballistics much except for the simplistic velocity/energy charts from ammo lists.  I always thought faster would be less drift for the same bullet.  Turns out drift is related to the rate at which a bullet sheds velocity.

This does not address terminal performance for hunting.  Here I had to go anecdotal.  Many experienced shooters report good killing power and penetration from round balls to 100 yards.  I have no personal knowledge.  I do know that my .444 Marlin is a better large animal killer than a 7mm magnum to 200 yards.  I've shot enough moose with both to know.  Big heavy projectiles kill differently than the high speed small caliber stuff.  But they perform way out of scale for what thier energy figures suggest. 

The last unknown for my research is the effect of the passing from sonic to subsonic velocities.  Target shooters want thier bullets to stay in either range from muzzle to target.  What do round balls do when they drop from sonic to subsonic?