I used my chronograph for the first time yesterday to check the velocity I'm getting with my handloads. The variation in velocity was more than I expected. Is a standard deviation of 21 fps typical? Should I be disappointed? If so, what should I do to try to reduce the variation? Velocity results and component info is below:
10 shots over ProChrono Digital
Temp 30F
Chrono was 15ft from muzzle; sun diffusers in place
Max vel: 3,072
Min vel: 3,003
ES: 69
Average: 3,055
St. Dev: 20.9
Note: The cold bore shot was 3,003 fps. The next lowest was 3,023.
Load is 165 gr. Barnes TSX over 72.8gr IMR 4831 with Rem LRP and Win Brass (twice fired, trimmed if necessary). COAL is set to the max that will feed in the magazine (rifle is Ruger Hawkeye).
I use a Dillon RL550 to load, but I don't use it as a progressive. I size/deprime and then measure for length. I then prime, rotate, drop a charge, remove the case and measure the charge on my scale, trickle in powder until I reach my weight. Put it back in the shell holder, rotate into position and seat the bullet. I know my powder variation is not more than 0.05 grains according to my scale.
Thanks for any comments. I've never used a chrony before, so I don't know what "good" velocity results are.
10 shots over ProChrono Digital
Temp 30F
Chrono was 15ft from muzzle; sun diffusers in place
Max vel: 3,072
Min vel: 3,003
ES: 69
Average: 3,055
St. Dev: 20.9
Note: The cold bore shot was 3,003 fps. The next lowest was 3,023.
Load is 165 gr. Barnes TSX over 72.8gr IMR 4831 with Rem LRP and Win Brass (twice fired, trimmed if necessary). COAL is set to the max that will feed in the magazine (rifle is Ruger Hawkeye).
I use a Dillon RL550 to load, but I don't use it as a progressive. I size/deprime and then measure for length. I then prime, rotate, drop a charge, remove the case and measure the charge on my scale, trickle in powder until I reach my weight. Put it back in the shell holder, rotate into position and seat the bullet. I know my powder variation is not more than 0.05 grains according to my scale.
Thanks for any comments. I've never used a chrony before, so I don't know what "good" velocity results are.