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PostPosted: Fri Apr 14, 2017 2:48 pm 
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Joined: Fri Apr 14, 2017 2:26 pm
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I have an Anschutz 1712 Silhouette that I have been trying different makes/models of .22lr through to look for the best average group size. I shoot outdoors with a stiff and changing crosswind, which tends to stretch groups out horizontally at distance if I'm not actively doping for the wind. In general, the more expensive rounds tend to give statistically better groups at all distances, which is not very surprising. But this weekend I found that Lapua Center-X is my new record-holder for average group size at both 50 and 100yd, beating out even Midas+. Both beat all prior competitors for average group size, even Eley Match which was my prior best.

Now before I run off and buy a case of Center-X, I'm curious what effect the choice of lots may have since I've only shot 1 box of it. The difference in average group size was 0.05" at 50yd and 0.03" at 100yd, though the latter is not likely to be statistically significant. The lots were:
Center-X lot 27551 602236
Midas+ Lot 26551 503251

Since I'm new to choosing ammo:
* 1. Do you find enough variance between lots that I really ought to sample several lots of each type? Do I need more data?
* 2. If this Center-X lot really does match my rifle well, are there tables people (or the manufacturers?) keep to help guess at alternate lot numbers to try? I'm wondering if some other Midas+ lot would be even better but I'm not sure that just buying several boxes from different lots is the best approach. Or has anybody put the data together that could help me guess at e.g. Eley or RWS lots to try given these lot numbers?
* 3. Other hints?


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PostPosted: Fri Apr 14, 2017 4:38 pm 
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Joined: Sat Nov 15, 2008 4:20 pm
Posts: 4895
Location: Scottsdale AZ
Is this real? It makes ME laugh.


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PostPosted: Fri Apr 14, 2017 5:52 pm 
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Joined: Fri Apr 14, 2017 2:26 pm
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Rover wrote:
Is this real? It makes ME laugh.


Yes it's real, I honestly don't know how people manage lot #s and I'm curious.

* Does the variance in group size between lots of the same ammo type ever exceed variance between ammo types? Can that explain my variance between Center-X and Midas+?
* I've heard a rumor that Lapua will test your rifle and help make lot recommendations; is there a shortcut I can take based on the lots that worked well for me in the past? Or am I left just to try a bunch?

Seems like reasonable questions to me :-p But please help educate me if I'm missing something ridiculous...


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PostPosted: Fri Apr 14, 2017 7:37 pm 
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Joined: Sat Nov 15, 2008 4:20 pm
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Location: Scottsdale AZ
" Does the variance in group size between lots of the same ammo type ever exceed variance between ammo types?"

OK I won't laugh, but this is well known in pellet testing and the answer is "yes." The ONLY thing that matters is lot number, not ammo brand.


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PostPosted: Fri Apr 14, 2017 7:47 pm 
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Joined: Mon Nov 29, 2004 2:49 pm
Posts: 2274
Location: Valencia County 4-H, NM USA
I can't remember the formula, but from my previous testing at Nammo in Mesa,

The Center-X lot ... starting w/ 275 denotes initial mfgr tests shooting 1072fps
The Midas+ lot ..... starting w/ 265 again denotes an initial testing of at 1068fps

I usually try and start testing at the same velocity as the previous lot I selected, but I know a barrel can change pretty drastically in what it likes. A lot depends on how often you shoot that gun in between tests, and even on a myriad of other factors ... weather, etc.

FWIW: My daughter shoots about 10K rounds per year, and like I said I usually start with last years velocity and type as a starter. In between freshman & sophomore year went from a 1072fps Center-X to a 1076fps STD+. In between her sophomore year & junior , the gun went to liking another 1076fps Center-X. Before senior year it liked nothing and us replacing the barrel and going to a 1079fps Midas+.


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PostPosted: Fri Apr 14, 2017 8:06 pm 
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Joined: Sat Sep 17, 2016 6:53 am
Posts: 13
Location: Houston, TX
mbryan wrote:
* I've heard a rumor that Lapua will test your rifle and help make lot recommendations;


Not a rumor at all... http://www.lapua.com/en/resources/test-shooting.html


Quote:
... is there a shortcut I can take based on the lots that worked well for me in the past? Or am I left just to try a bunch?


Some shooters that use Eley ammo have created a correlation between average batch speed and machine number to find a combo that generally shoots as well as others within that same speed/machine combination, but it takes multiple speed/machine/batch testing to create that kind of correlation.

Most people in your situation will test particular batches and when they find one that shoots "good enough" they just buy as much of that batch as they can afford (multiple cases).

Good luck with your ammo search.


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PostPosted: Sun Apr 16, 2017 9:40 am 
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Joined: Mon Mar 22, 2004 6:03 pm
Posts: 250
Location: ...ain't in Texas no more....
acorneau wrote:
mbryan wrote:
* I've heard a rumor that Lapua will test your rifle and help make lot recommendations;


Not a rumor at all... http://www.lapua.com/en/resources/test-shooting.html


Quote:
... is there a shortcut I can take based on the lots that worked well for me in the past? Or am I left just to try a bunch?


Some shooters that use Eley ammo have created a correlation between average batch speed and machine number to find a combo that generally shoots as well as others within that same speed/machine combination, but it takes multiple speed/machine/batch testing to create that kind of correlation.

Most people in your situation will test particular batches and when they find one that shoots "good enough" they just buy as much of that batch as they can afford (multiple cases).

Good luck with your ammo search.


The speeds published on the Eley boxes only correlate to the speed measured at their facility. It does not translate to other chronographs, but it is consistant from lot to lot.

It is not worth tracking the Eley machine numbers as the machines are constantly overhauled with parts removed and overhauled from the other machines.

Test and find the lot that shoots best in your rifle. Buy as much as you can.
Regards
ken


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