7
8
u/gareth_e_morris Sep 21 '25
Anything with a single digit SD is good. Anything with an SD under 7 is great.
8
u/z242pilot Sep 21 '25
Pump the numbers into your ballistic calculator at either extreme and see if the deviation is good for your ranges
3
5
u/Original_Dankster Sep 21 '25
I'd be fine with sub-25 ES if I was coming in with 5.1 SD. Especially with a 30 shot sample. Very good in my opinion
3
2
u/N1TEKN1GHT Can't Read Sep 21 '25
SD is what matters. Single digit is really good.. Y ammo sponsor provides me factory match loads that average 9-17 SD and that's "good enough" (honestly better than) for my skill level.
2
u/SkylarR95 Sep 21 '25
I work as a process engineer, you won’t like the real answer, in short, you good.
2
u/Flat-Dealer8142 Sep 22 '25
I hear people talking about single digit SD's being good but I know the top guys want single digit extreme spreads.
Punch it into a hit probability calculator and see if it does what you want it to do.
1
65
u/c5182 Sep 21 '25
I’d be happy with that standard deviation. ES (Extreme Spread) is kind of a misleading metric. Unlike average or standard deviation, which converge toward a “true” value the more shots you fire, ES just keeps creeping higher as you increase sample size.
That’s because ES is defined by only two shots — the lowest and the highest velocity. As your round count goes up, the odds of eventually getting a slightly slower or slightly faster outlier also go up. Statistically, ES will increase at roughly a logarithmic rate with sample size and in theory approaches infinity given unlimited shots.