I finally found some time to do some shooting.
Actually, I am testing to find the best load for a particular bullet, the Paul Jones Creedmoor which drops at 560 grains from my NEI mould.
I am shooting this slug from a .45-90 case in a Pedersoli Sharps rifle. Range was 100 yards.
I loaded these test rounds back in May, and fired them yesterday - temperature 80°, humidity 25%. Fired four 'sighters' to get on the paper, and ran one damp patch between shots for the entire session.
I wasn't trying for a 'clean barrel'...just a consistent one.
I suspect that my bullet alloy is softer than it should be. The 'tin' I bought to make up 20-1 alloy turned out to be only 25% tin...so my alloy didn't come out right. Maybe that's why my bullets weigh 560 grains from a mould that's supposed to throw them at 540 grains.
Anyway, I am willing (for now) to blame poor groups, in the stiffer loadings, on 'slumping'...at least until I get my alloy refigured.
All loads had the bullet seated to the same depth of .665" so only the amount of compression changed as the powder was increased. Charges (of GOEX Cartridge) were:
1st group fired - 75 grains - Smallest five shot group, 1 inch high and 3/4 inches wide.
Average velocity, 1187 - std. deviation 14.76
2nd group fired - 79 grains - Loose group 1 inch high and 3 inches wide.
Average velocity, 1183 - std. deviation 8.24
Last group fired - 80 grains - Poorest group 3 inches high by 2 1/2 inches wide.
Average velocity, 1143 - std. deviation 16.24
This was the first time I have ever used a chronograph. I was hoping it would tell me all kinds of 'magical' things. I do find it interesting to know all of those little details within a shot string, but...
Can anyone provide a reason...or a theory...about why
"more powder means slower bullets"?
CM