For a long time i've been aware that velocity goes higher when a powder charge is compressed. This was recently confirmed when a friend and i tested Alliant Black MZ using his Oehler 43 personal ballistics lab and my TC Encore rifle.
This gentleman took his testing much further. He got an increase of over 100 fps when the powder charge was compressed. His charge was 30 grains of Swiss BP driving a PRB. He also proved that a low standard deviation for velocity is not everything: Compressed Loads
Since compression is hard enough to judge, I decided to test only four variations: |
- 'Loose' - The ball placed 1/4" above the top of the powder.
- 'Normal' - The ball seated with about one pound of pressure.
- 'Compacted' - The powder compressed hard, then the ball seated.
- 'Whanged' - The ball and powder compressed together.