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Old January 12, 2002, 03:21 PM   #1
Peter M. Eick
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Join Date: August 3, 1999
Location: Houston, Texas
Posts: 2,991
Are large differences in SD between guns common?

I was out shooting 9mm a few days back and I noticed with the same run of reloads the following averages for standard deviation for different pistols:

Sig 210-6 average sd 12 fps
Hk p7psp1 average sd 33 fps
Hk p7psp2 average sd 23 fps
Hk p7 average sd 19 fps

These are all with the same reload run (berry 115 rn with 6.0 grns power pistol, starline brass, cci500 primers). All measurements were from 20 shot strings at about 10 feet with a 35p chrono.

I was expecting some small variations say 2 to 5 fps, not that big. Also I did notice that each guns velocities were very consistent, ie: the high and low and average were very close.

Any insights?
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