What is an "acceptable level" of variation in bullet velocity for hand loads? Is it .1%, .5%, 1% deviation from the average?

I can sometimes average 1% which seems too much to me. Am I wrong?

Thanks,
John

Dasmoofler,

Welcome to the forums.

I think the factories use a +/- 35 fps - at least that is what I have heard.

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saeed@ emirates.net.ae

www.accuratereloading.com

I was once told that if your load shoots well but has a large SD change primers, and that might derease the SD. I like to see 20fps or less with my handloads, but accuracy and the velocity/energy to do the required job are more important to me than a low SD figure.

I've rarely seen factory loads that would consistantly vary less than 35 FPS + or -. Generally, the faster the powder, the greater the variation, and the slower the powder, the less the variation. Since factory loads always use powders in the faster range for a given cartridge (it's cheaper, dummy!), they usually vary more than well-assembled handloads.

Using slow powders like surplus 4831, H570, H870 and WC 872, I normally expect variations less than 20 FPS.

With a powder like 4198 or 3031, 75 to 100 FPS variation is not uncommon.

This does NOT, however, mean that low variation always gives good accuracy or that high variation always gives poor accuracy.

I've had cartridges like the .222 shoot under 1/2 inch with loads that varied by 100 FPS.

All things being equal, however, the less variation the better.

Well, if you constantly get 1/2", 200-yard, 10-shot groups, who cares about the standard deviation?

The factory loads I have tested turned in standard deviations of 35, just as stated before. If you hand weigh loads, and sort bullets by weight, you can get down into the high teens-low twenties. My 29" Swede regularly turns in very low standard deviations, pretty much regardless of what I feed it.

With a standard deviation of 35, 95% of your rounds will be within plus or minus 70 fps of the average.

Thanks everybody,
Although I'm not getting 1/2" groups @200 yds, I can get that @100 if I do my part. This is good enough for deer and 'yotes, but I still have some work to do if I want to do prairie dogs!
Thanks,
John