Bullets Posted June 29, 2016 Share Posted June 29, 2016 Just curious what most peoples standard deviation is. What is considered to high? Link to comment Share on other sites More sharing options...
js1130146 Posted June 29, 2016 Share Posted June 29, 2016 (edited) I shoot for a single digit SD. Anything more than 10 and the load gets re-evaluated and reworked to see if I can get it lower. Edited June 30, 2016 by js1130146 Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted June 30, 2016 Share Posted June 30, 2016 I look more at accuracy and PF. Link to comment Share on other sites More sharing options...
js1130146 Posted June 30, 2016 Share Posted June 30, 2016 Consistency should, in theory, lead to accuracy. But yes, always gotta hit that PF requirement. Link to comment Share on other sites More sharing options...
Sarge Posted June 30, 2016 Share Posted June 30, 2016 Low teens is decent. Single digits is what I like. 4 is the best I ever got. I did that with n320 in 9minor. I'm at 7 with my current 9MAJOR load using WAC Link to comment Share on other sites More sharing options...
Bullets Posted June 30, 2016 Author Share Posted June 30, 2016 Im at 10.18 right now. What are things that effect the sd? Bullet weight variances? Usind xtreme. Mixed brass? Using mostly fc and speer. Uneven charge weight? Make sure it stays under.1 every drop. Anything else? Crimp? Im crimped to .376 outside diameter at case mouth. Oal? im getting about .04 variance. Link to comment Share on other sites More sharing options...
Sarge Posted June 30, 2016 Share Posted June 30, 2016 In my experience all of the following play a big part in it: Lube cases. Sort by head stamp. Consistent operation of the press. Stopping the press to keep measuring powder drop, oak, crimp etc skews all of those readings Link to comment Share on other sites More sharing options...
js1130146 Posted June 30, 2016 Share Posted June 30, 2016 What's your current load? Some powders don't play nice with certain loadings, but that's normally very light or very heavy powder charges having ignitions issues. Link to comment Share on other sites More sharing options...
RDA Posted June 30, 2016 Share Posted June 30, 2016 In my experience all of the following play a big part in it: Lube cases. Sort by head stamp. Consistent operation of the press. Stopping the press to keep measuring powder drop, oak, crimp etc skews all of those readings I'd also add that the type of powder can be significant, I see much lower standard deviations with certain powders over other powders (all else being equal). Link to comment Share on other sites More sharing options...
Bullets Posted June 30, 2016 Author Share Posted June 30, 2016 I have a few that i use. All sd seems to stay between 10 and 15. Autocomp 5.4gr 115gr xtreme. N320 3.9gr 124gr xtreme.hs6 8.1gr 124 mg. 3.9gr titegroup with 115 xtreme. Link to comment Share on other sites More sharing options...
dauntedfuture Posted June 30, 2016 Share Posted June 30, 2016 You should be looking at ES and SD when you evaluate a load, especially for rifle. You can have a low ES and a high SD; that an indication that you did, or there was something inconsistent in that high or low round and you can work to identify and eliminate that variable. It could we sorting out xxx brand of pistol case or weighing rifle cases to find that one light or heavy case. Link to comment Share on other sites More sharing options...
Bullets Posted June 30, 2016 Author Share Posted June 30, 2016 Here is a 10 shot string. Sd was 10.63 1396 1387 1376 1393 1362 1390 1373 1386 1374 1386 Link to comment Share on other sites More sharing options...
MemphisMechanic Posted July 11, 2016 Share Posted July 11, 2016 (edited) If that is accurate at 25yd and it makes power factor comfortably (2 X S.D. for safety at major matches = roughly 20 fps above the minimum for PF over a chrono) ... run with it. However. If you just feel like tinkering... First thing I look at is OAL. Take a caliper to your rounds and see how much they vary. If I target 1.130" I often see 1.1.27"-1.135" come out of my 650 with mixed headstamps. You can load all of your test ammo in matching headstamps cases to further increase consistency - it'll shrink your OAL variation and also remove changes in volume due to different wall thicknesses. If you get a good SD with that, but it opens up with mixed brass, then you know your powder measure and handle-rowing technique are doing their job. Keep using mixed brass with confidence at local matches, and if you decide you care, go with a single headstamp at majors. (Most of us production shooters don't bother. I switch to Federal primers for majors instead of my usual CCIs, and keep rocking mixed brass) Edited July 11, 2016 by MemphisMechanic Link to comment Share on other sites More sharing options...
jmorris Posted July 11, 2016 Share Posted July 11, 2016 SD is not the end all for me. I have had some loads that were single digit but were less accurate than another load that may vary much more. Of course you would still want your load to always make power factor year round, a lot more important for pistol matched than SD. Link to comment Share on other sites More sharing options...
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