Satterlee 10 Round Load Development

[centerfire]

Centrefire,

Well, at least we agree that Satterlee does not work in all situations.

And if you want to compound the validation by suggesting it is not working because the OAL is not being tested and lots of different powders are not being tested then again, how will you ever know that the lowest SD/velocity spread produces the best results at 1K unless you test all of these other permutations across all other loads to produce the tightest groups at 1K?

Are you saying that because my SD's were not low enough across all loads that it somehow confounds Satterlee, and that Satterlee only works with single digit SD's? Surely, as long as all variables across all loads are equal that shouldn't matter. Yes, I could now tinker with powder and primers and technique to tighten the groups further (and in doing so tighten the SD's) but how much of doing this is enough to qualify for Satterlee?

Tightest groups is not a sidebar, this is what you are trying to predict at 1K. Finding the tightest velocity nodes with the lowest round count at the muzzle is not the aim of the exercise, it is the mediating variable to finding the tightest groups at long range. And in this situation it did not work.

What I'm saying is that your spreadsheet suggests your single digit SD's surrounded by high SD's are telling you that your load is going to have vertical stringing problems as soon as you introduce environmental variables. The purpose of testing for velocity nodes is to find a load that is insensitive to pressure changes, beit heat or imprecise powder charges. Once you find a acceptable node, regardless of group size, you then shoot seating depth groups looking for the best accuracy. I would absolutely reshoot that low SD group and charges surrounding it to validate that your chrono results are actually accurate with larger samples. Ignore the group size until you start to work on it with seating depth adjustments.

I'd be willing to bet those low single digit SD's on the spreadsheet are actually much higher when you either shoot more groups or larger round count groups. Further, if you only shoot those 223 loads at 300 yards then most of this is just academic because you likely won't see a difference inside of 600 yards. The "Satterlee Method" attempts to locate the flat velocity nodes in a small number of rounds, not find the tightest group. As you pointed out, it is statistically irrelevant and often when you do a lot chrono testing (as you did), you identified nodes aren't really nodes after all. Try shooting the 23.5gr group again with 10 or 15 rounds and see what the SD's are.

Personally I would not use that load without more validation. 8208 does change velocity with heat and it wouldn't take much to change your velocity enough to swing the ES and SD's. I shoot a lot with some fairly competitive F-Class shooters and they would not use what you posted no matter what the group size is at 100 yards.

Also, thank you for taking the time to test this out and posting it for everyone to see. This is valuable for everyone following it.