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Standard Deviation

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16 January 2010, 03:11
Bill73
Standard Deviation
To all you experienced reloaders out there reloading for your Double Rifle,how many shots do you run over a chrono ? before you are happy with the way your load is shooting,what are you happy with for standard deviation between shots ? what in your opinion gets the lowest deviation between shots ? what was the lowest deviation that you ever got ? thanks for your replies gents !!


DRSS
16 January 2010, 07:16
465H&H
I keep the chrono going while I am checking regulation of loads. I don't pay any attention to sd. If they group and are at regulation velocity, I'm good to go.

465H&H
16 January 2010, 07:56
vapodog
Mathematics of standard deviation suggests nine rounds is required before the number actually is meaningful

However I agree....it's really not too important.

especially for a short range cannon!


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16 January 2010, 08:03
sharpsguy
I have chronographed tens of thousands of rounds testing black powder in cartridges. Low sd numbers have no real bearing on accuracy, at least not until distances approach 500 yards.

Properly loaded black powder cartridges routinely produce sd numbers in the single digits. I have achieved an sd of 1 on a number of occasions. My match ammunition usually runs around 3 for sd, but I see no difference in vertical dispersion with sd numbers in the 5 to 7 range out to 1000 yards.

At hunting distances, sd will have no effect whatever on your accuracy. Load for a velocity that will cause your load to regulate and don't worry about the sd.