ACCURACY AND POWDER CHARGE VARIATION

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  • Last Post 11 January 2018
joeb33050 posted this 15 December 2017

 

ACCURACY AND POWDER CHARGE VARIATION

 

Savage Striker, 22-250, Savage M11 barrel cut to 16.5 inches, Weaver T36 scope, Nosler 53 gr. Varmageddon bullet, Titegroup powder, 4 @ 8.5 gr.; 1 @ 8.2 gr. all weighed = 5, 10 sets of 5, 100 yard 5 shot groups.

 

10 group avg. group size = 1.223”. Group 7 had 2 shots yanked; less group 7, avg. group size for 9 groups = 1.044”.

 

Arrows = 8.2 gr. shot/hole.

 

 

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Ross Smith posted this 15 December 2017

JoeB: Ah, Results, that's what all of this is about. How well prepared was the brass and bullets? Pretty strictly I'll bet and that's good, we should only have one variable at a time.

I too took some of my well prepared, weighed and sorted brass so the cases  were only .2 grns difference, and one group of unsorted brass. All 3 groups of brass were the same headstamp. I only shot six 5 shot groups which hardly proves anything but wouldn't you know it, the best group was the un-sorted brass! I still think the 5% is accumulative and if we are off 5% on brass, 5% on bullets, and 5% on powder things will fall apart.     Fourtunately, 5% is pretty easy to beat and should not scare away any new casters, or beginners.

I hope this didn't hijack your post. Ross

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joeb33050 posted this 16 December 2017

 

In 4 or 5? of the groups, the 8.2 gr hole is one of the furthest apart holes.

 

My records show, for the same gun etc load, 8.5 Titegroup, .878” avg. group size for 15 groups.  

 

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John Alexander posted this 16 December 2017

Joe,

Am I understanding the significance of this?  Your results seem to indicate that having the a powder weight variation of about 3.5% enlarged the groups?

John

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joeb33050 posted this 16 December 2017

Data is messy, one of my rules. The test groups are larger than the historical groups, but the historical groups were messy. 9 of the 10 groups weren't much larger than history. The 7th group was me, yanking twice. The 8.2 gr groups did not show up low all the time. Of the 10 groups, 4 or 5 groups had one of the two widest = 8.2 gr. Of the 20 sets of widest apart shots, 4 or 5? were 8.2 gr shots, wouldn't we expect each shot, #1 for ex., to be a widest apart shot about 4 or 5? times.

A test like this has no short declarative sentence results, except perhaps "Groups of 4@ 8.5 gr and 1 @ 8.2 gr aren't wildly inaccurate."

As always, more data is needed. Perhaps more analysis would help, I'd be happy to send a bigger clearer picture of the target to anyone.

joe b. 

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John Alexander posted this 17 December 2017

Thanks Joe. I hadn't read your post carefully enough.  In fact if four groups had one of the 8.2 loads as one of the 20 shots that were that were measured that would be exactly what would be expected (one out of 5) and would imply that there is no indication that the 8.2 loads degraded accuracy.

I think a better measure than one of the two shots to be measured would be check how often  the shot with the odd powder charge is the one that is out of the best four shot group. If the shot that expands the 4 best shot group is the odd powder charge 20% or less of the time it would be hard to argue that the low powder charge hurt accuracy.

Stated another way,  How often is the odd charge not in the best four shot group? If less than 20% of the time there is no support for arguing that the odd charge hurts accuracy.

John

 

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joeb33050 posted this 11 January 2018

Does this help?

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