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Sorting Center-X rim to ogive

I’ve sorted thousands of rounds of Lapua Center-X with the Neco gauge. The gun used is a 40X with one of Lee’s lightweight tuners. I found groups shooting sorted ammo had fewer fliers than the same lot of un-sorted ammo. While I didn’t record the data, I did see it on the targets. The plan this season is to record the results and determine if the gun has a preference for specific rim to ogive lengths.

The current lot shows less extreme spread in lengths than other lots I’ve sorted.
The pic below shows the frequency of lengths- 100 rounds were sorted. (in about 15 minutes).

7F362E18-D7D9-401D-AFB4-12D9C0FBF2F1.jpeg
 
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I’ve sorted thousands of rounds of Lapua Center-X with the Neco gauge. The gun used is a 40X with one of Lee’s lightweight tuners. I found groups shooting sorted ammo had fewer fliers than the same lot of un-sorted ammo. While I didn’t record the data, I did see it on the targets. The plan this season is to record the results and determine if the gun has a preference for specific rim to ogive lengths.

The current lot shows less extreme spread in lengths than other lots I’ve sorted.
The pic below shows the frequency of lengths- 100 rounds were sorted. (in about 15 minutes).

View attachment 1245515
i do that too..
 
Ok, so my question is - "how much variance is too much" and how do you know without data? I am not saying I don't believe you. I just know from rim thickness sorting 100's of rounds, everytime I think I've found some corilation, when i try to prove it statistically, I can't. If your hypothisis is valid, how do you group your ammo and then how do you change your tune for the various groups?

Have you "lot tested" the CX, and if so, are sorting the same lot?
 
Ok, so my question is - "how much variance is too much" and how do you know without data? I am not saying I don't believe you. I just know from rim thickness sorting 100's of rounds, everytime I think I've found some corilation, when i try to prove it statistically, I can't. If your hypothisis is valid, how do you group your ammo and then how do you change your tune for the various groups?

Have you "lot tested" the CX, and if so, are sorting the same lot?
i took my gauge with me to the test center when i was up there early March.. one thing i found.. the ammo that shot the best in the rifle, had the same ogive to rim distance
 
Ok, so my question is - "how much variance is too much" and how do you know without data? I am not saying I don't believe you. I just know from rim thickness sorting 100's of rounds, everytime I think I've found some corilation, when i try to prove it statistically, I can't. If your hypothisis is valid, how do you group your ammo and then how do you change your tune for the various groups?

Have you "lot tested" the CX, and if so, are sorting the same lot?
Sorting the current lot I have with the best tuner setting I found so far shot several 5 shot groups in the low 1’s. Unsorted ammo often had one round that was a bullet width or more away from the group. That is too much variation. The gauge doesn’t measure rim thickness, it measures from the front side of the rim to the “ogive”.
So far I’ve grouped the ammo to length, eg, all 25 or all 26 lengths. I found the tune that shoots both these lengths the smallest. Not enough experience yet to distinguish 0.001” difference in length, probably never will.
I have sorted and test shot the same lots. Before sorting, the shots out of the groups were deemed to be me or a missed wind change. The issue first surfaced in a lot that varied from 23 to 29 on the gauge, fliers were greatly reduced shooting the same length.
Ive got a lot more shooting to confirm the value of this kind of sorting but so far I’m encouraged to continue.
 
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When I started sorting ammo, I would sort a box (using cheap stuff, so 100 rounds) then match the number of culls with what I considered my most consistent, then a group of the same number second best.

Culls being rounds so different there were only say or less and on the extreme outside measurements. The tighter the tolerance the more groups.

Then shoot these best to worse or worse to best at the same target in large sample groups. I tried for 20 minimum.

Shoot the 10/20 best, take a picture and measure, shoot the next group, picture and measure. The overall group should grow at each change of ammo, or basically sorting it made no difference.

Plugging the photos into one of the group measuring apps was telling.

The better the ammo gets, the fewer culls, but if every cull is a flyer......
 
Sorting the current lot I have with the best tuner setting I found so far shot several 5 shot groups in the low 1’s. Unsorted ammo often had one round that was a bullet width or more away from the group. That is too much variation. The gauge doesn’t measure rim thickness, it measures from the front side of the rim to the “ogive”.
So far I’ve grouped the ammo to length, eg, all 25 or all 26 lengths. I found the tune that shoots both these lengths the smallest. Not enough experience yet to distinguish 0.001” difference in length, probably never will.
I have sorted and test shot the same lots. Before sorting, the shots out of the groups were deemed to be me or a missed wind change. The issue first surfaced in a lot that varied from 23 to 29 on the gauge, fliers were greatly reduced shooting the same length.
Ive got a lot more shooting to confirm the value of this kind of sorting but so far I’m encouraged to continue.
I have a suggestion and that is replace the dial indicator with a good Mitutoyo digital. it is much easier to sort and have a number such .750 vs .755 instead of 25, 26 etc.
also when you find a great shooting lot check the length and record it. then next time you have test lots check them and grade them per length test shoot them that way cuts testing real quickly.
I can by length checking alone know how it will shoot in any of my rifles. before I shoot any.

this is the same thing CF shooters do to find a load, except they can alter the OAL by reloading.

Lee
 
I have a suggestion and that is replace the dial indicator with a good Mitutoyo digital. it is much easier to sort and have a number such .750 vs .755 instead of 25, 26 etc.
also when you find a great shooting lot check the length and record it. then next time you have test lots check them and grade them per length test shoot them that way cuts testing real quickly.
I can by length checking alone know how it will shoot in any of my rifles. before I shoot any.

this is the same thing CF shooters do to find a load, except they can alter the OAL by reloading.

Lee
Hey Lee-
I expect to get the digital indicator you suggest at some point.

Have you found your rifles prefer a specific length or just not a wide range of lengths?

Art
 
Hey Lee-
I expect to get the digital indicator you suggest at some point.

Have you found your rifles prefer a specific length or just not a wide range of lengths?

Art
Art,
I found and this is going by a digital indicator .725-.730 shoots real good. also my chamber is by design only gives 0.030 engraving off the ogive. but as you found out the more consistent the length the better it will shoot regardless, so sorting them to be in one group length does help.

Lee
 
Art,
I found and this is going by a digital indicator .725-.730 shoots real good. also my chamber is by design only gives 0.030 engraving off the ogive. but as you found out the more consistent the length the better it will shoot regardless, so sorting them to be in one group length does help.

Lee
Lee,

Ok, that’s what I thought. I‘m wanting to get there with my rifle.

Art
 
I have a suggestion and that is replace the dial indicator with a good Mitutoyo digital. it is much easier to sort and have a number such .750 vs .755 instead of 25, 26 etc.
also when you find a great shooting lot check the length and record it. then next time you have test lots check them and grade them per length test shoot them that way cuts testing real quickly.
I can by length checking alone know how it will shoot in any of my rifles. before I shoot any.

this is the same thing CF shooters do to find a load, except they can alter the OAL by reloading.

Lee
what i found out was that .741 on my gauge, seems to be the number for the rifle i had tested
 
Have you seen this for any lot? meaning sorted by .741 will shoot regardless of speed

Lee
yes at the test center.. one lot of Center-X and one lot of Midas + and both were measuring the same length on my gauge.. and both shot really good.. the Midas shot better at 100 meters than the Center-X but they both shot the same at 50 meters.. i am sure that you can figure out which lot i bought and i bought what was left.. two cases


The Midas+ was 325
The Center-X was 328
 
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I’ve sorted thousands of rounds of Lapua Center-X with the Neco gauge. The gun used is a 40X with one of Lee’s lightweight tuners. I found groups shooting sorted ammo had fewer fliers than the same lot of un-sorted ammo. While I didn’t record the data, I did see it on the targets. The plan this season is to record the results and determine if the gun has a preference for specific rim to ogive lengths.

The current lot shows less extreme spread in lengths than other lots I’ve sorted.
The pic below shows the frequency of lengths- 100 rounds were sorted. (in about 15 minutes).

View attachment 1245515
I tried to find this gauge on the Neco site and had no luck. Is there a part number or specific name for it? Thanks,
 
i took my gauge with me to the test center when i was up there early March.. one thing i found.. the ammo that shot the best in the rifle, had the same ogive to rim distance

where approximately, on the ogive, is your reference point for measure?
Front or back side of rim?

thx, jim
 
I tried to find this gauge on the Neco site and had no luck. Is there a part number or specific name for it? Thanks,
I believe they discontinued the gauge. Contact NECO, they have responded to emails.
Its the G3 MK II Rim-to-Ogive Gauge
 
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