Acceptable Es/Sd?

[Nimbus73]

I just found this thread after I posted a how good is good enough brain sneeze question. LOL

 

[Koda_]

Thanks for the replies. Seems that single digit ES/sd really are not that important for the accuracy and distance I am expecting. I still think I will strive for 30ish ES, but maybe not get so hung up on it, if it is more than that.

I am curious what most of you guys consider good or acceptable Es/Sd? Trying to get a good baseline for where I should be at. Typically I look for an ES of 30 or less thru 5 shots. It has worked out, but wondering if I should strive for lower even tho it groups good.

Its interesting that max ES/SD isnt more widely documented, its taken me a while to find articles on this. Ive read max limit baselines for extreme spread between 25 and 35fps is acceptable as "good" but when Ive read an article from a benchrest shooter perspective max ES should be sub 10fps. I watched a video from Eric Cortina on ES to find more and from his perspective if your ES is not low something is wrong.
So the question then is what ES is acceptable for hunting, is going to be based on how far you hunt. The only article Ive found that discusses this shows the vertical dispersion of different ES's at various distances and if I extrapolate this chart to 600yds I estimate 2.85 inches vertical displacement which to me I would want much better than 25ES by at least half where if I never hunted past 300yds 25ES would be fine.
All other things being equal (perfect shot placement every time).

Long Range Shooting: Understanding Extreme Spread And Standard Deviation - Guns and Ammo

With the increase in interest in long-range shooting, the terms extreme spread (ES) and standard deviation (SD) are being thrown around a lot.

www.gunsandammo.com

 

[SamsonMan22]

There’s some voodoo magic chit to ES/SD. I can use the same reloading practices and same types of dies and sometimes I get great numbers, sometimes I don’t. As long as it shoots acceptable groups, I try not to worry about it.

Except I do have one gun that drives me nuts. It shoots several loads into easy sub 1/2 Moa, but everything thru that barrel has massive spreads, like 80+. It bugs me, but even at that I don’t think I notice it on a target.

How are you measuring powder? I ask because I had the same deal when using a charge master lite. Often I would load ammo in 200 round batches and take random samples of 20 and run them over the chrono. Sometimes es was in the 20s and sometimes in the 50s. Average velocity would fluctuate between lots as well.

When I started throwing charges with a Harrels my es on average increased slightly but over the course of several 200 round lots the es didn’t really change and neither did the average velocity, at least not an amount that could be measured on target. I just keep the setting recorded for a given charge weight and set it to that for each cartridge/ powder combo. In the end my ammo on the chrono looks less consistent but on target it’s more consistent and lot to lot variation is near non existent.

To answer the OP I don’t worry about it at all anymore for the ranges I shoot (sub 1k). I let a 20-30 round group at 100 dictate if the load is good and that’s it. I only use a chrono to get a rough idea on velocity for a calculator. Some of my best shooting loads at distance are 60-80 for the es.

 

[SDHNTR]

I measure powder on a Matchmaster, and I double check weigh every 6-8 loads on a balance beam. It’s all within a kernel.

 

[Pharmseller]

I don’t pay attention to SD.

Under 35 for ES.

I don’t shoot past 600 yards, though.




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