bullet sorting BTO, how fine of a resolution is needed ?
- Thread starter JimSC
- Start date
Sorting and analyzing your bullet sorting
I wanted to share data from this weekend’s sorting of bullets using my new product, Sorteez. You can find more information about Sorteez at www.barrelcool.com/product/sorteez. Shipping for this product will be this week. The beauty of Sorteez is that you can now document your sorting sessions...
forum.accurateshooter.com
Bullet Sorting?
I sort all my batches of bullets base to ogive using a Sinclair sorting stand,my questions are if I was to sort two different batch numbers of the same bullet and they were within +/- .001" (2 thou difference) of one another would you call it good and carry on with same load? Or if the variance...
forum.accurateshooter.com
Thanks for the replies but neither of the threads linked went into detail as to what I want to know. My bad, I suppose I was not clear.
My untested theory is that ES/SD numbers will be affected because of the varying amount of the bullet base that will be inserted into the neck will affect case volume slightly. Possibly causing a spread in velocity ES
I will rephrase my original question. Has anyone tested as to whether bullets with plus or minus .001 or bullets sorted into plus or minus .003 grouped better or provided better ES/SD numbers. Has anyone here ever really tested sorted vs non sorted and if so what differences did you see. Also did the differences show up at plus or minus .001, or plus or minus .002
My untested theory is that ES/SD numbers will be affected because of the varying amount of the bullet base that will be inserted into the neck will affect case volume slightly. Possibly causing a spread in velocity ES
I will rephrase my original question. Has anyone tested as to whether bullets with plus or minus .001 or bullets sorted into plus or minus .003 grouped better or provided better ES/SD numbers. Has anyone here ever really tested sorted vs non sorted and if so what differences did you see. Also did the differences show up at plus or minus .001, or plus or minus .002
Last edited:
oh these are more like plus or minus .010. My sort of 250 looked something like the pic in this artcle
Bullet Bell Curve — Sorting by OAL vs. Base to Ogive « Daily Bulletin
The USAMU recently published a how-to article about bullet sorting. While many of us may sort bullets by base-to-ogive length (and/or weight), the USAMU story explores the how and why of sorting bullets by Overall Length (OAL).
6BRA
Gold $$ Contributor
My last 500 bullet sort....from un named custom bullet manufacturer yield at most .0015 across 500 bullets.
most were within .001 and only maybe 10 bullets fell outside of this.
so I basically had 2 sorts with 10 foulers...the 2 sorts were within .0005...
Hollands Gold Standard Bullet Comparator was used....on these....
and I might say my groups are pleasantly happy....
most were within .001 and only maybe 10 bullets fell outside of this.
so I basically had 2 sorts with 10 foulers...the 2 sorts were within .0005...
Hollands Gold Standard Bullet Comparator was used....on these....
and I might say my groups are pleasantly happy....
Last edited:
Ned Ludd
Silver $$ Contributor
In my hands, length-sorted bullets generally group a bit tighter, but length-sorting does not seem to have much of an effect on velocity stats. However, I sort by OAL for the purpose of pointing bullets, not BTO. In addition, I have measured many of the bullets I use over the years (predominantly Berger), and I have found that the majority of OAL variance resides in the nose region, whereas the bearing surface/boattail segments seem to be much more uniform in length. Exactly where (i.e. boattail, bearing surface, nose) the majority of the length variance in your batch of bullets falls will likely impact whether sorting by BTO can improve ES/SD.
Variance in the amount of effective case volume due to bullet BTO length variance is analogous to the effect observed when changing seating depth. I have always found with jumped bullets that one can change the seating depth by as much as .010" to .015" in either direction without much effect on velocity. For example, let's say one has optimized charge weight with bullets seated at about .015" off the lands, and then tested seating depth from about .003" off to .033" off in .003" increments. To be sure, the average velocity for the group at each seating depth over that range may change by a few fps. But much of the observed velocity differential between groups is likely due to the small sample size, typically only 5 shots at each seating depth. Further, the average velocity differential between groups in a seating depth test is usually smaller than the ES within a single group.
If you're going to sort bullets by BTO, the length variance obtained in the sorted bullets should give you some idea of what magnitude of effect you might expect. If the overall range for bullets sorted by BTO length don't cover more than .020" to .030", I doubt you're going to see much of a consistent and reproducible effect on velocity. However, you may still find an effect on precision that makes sorting by that method worthwhile.
thanks that was the info I was looking for
and it will be F class off a bipod and shot prone, just using for practicing recoil management, 300 to 800 yards. If I can get ten shot 1 MOA groups in afternoon wind and mirage with these I will be a happy camper. I just want to be able to call my flyers and not wonder if it was me or the ammo. However now that my curiosity is up though I do plan on shooting a couple of 15 round groups over the chrono
Ned Ludd
Silver $$ Contributor
The good news is that length-sorting the bullets, or pretty much any other kind of sorting step, is never going to make anything worse. In a worst-case scenario, length-sorting has no appreciable benefit for the time expended. Otherwise, any observed improvement can then be weighed by the individual doing the sorting to decide whether the sorting process is actually worth the time expended. As I mentioned above, I'm guessing you may not see a big difference in ES/SD, but that's just a guess as I don't have any idea how much total BTO length variance is present in that particular Lot# of bullets. Even if sorting offers only a small benefit with respect to precision, it may well be worth the effort. To that end, you might also consider including some kind of "extremes" test such as loading a few bullets (each) from both the longest and shortest sorting groups, and a control set with bullets that have not been sorted. Best of luck with it.
My objective for sorting my bullets is for getting as much precision out of my cases as I can. Sorting by BTO was not doing well for me as I found substantial seating depth variances when measuring CBTO, which I found was due to the difference between my seating stem's contact point and where the contact point is on my caliper insert for my BTO measurements.
When load developing, it's often recommended in OCW testing to seat bullets at .003 increments to see the changes and find the depth that'll work the best. If .003 in seating depths makes enough difference that can be recognized, then that variance I see when measuring CBTO after seating that's greater than .003 is a problem in getting the precision I'm after. The best solution I've found for this is sorting my bullets BTO by using a comparator insert that has the same contact point as my seating stem. This way my seating depths are consistent, though the CBTO, as measured by my standard comparator insert, is not, which is not near as important as having the consistent seating depth. That is to say, having .003, or whatever, variation in distance to the lands is not as important as .003 variation in seating depth. . . as we often make out in OCW testing.
There can be significant difference between the bullet's meplat and the seating stem contact point too. If one is going to tip bullets, I'd certainly want to sort by bullet lengths . . . but then, sort again as I do to get consistent seating depths.
Sorting this way has made a nice difference, even for someone like me who does not use a high end gun, where my groups are mostly in .3 MOA size. I think that's about as good as I can get out of a factory gun with a good barrel (like Krieger).
When load developing, it's often recommended in OCW testing to seat bullets at .003 increments to see the changes and find the depth that'll work the best. If .003 in seating depths makes enough difference that can be recognized, then that variance I see when measuring CBTO after seating that's greater than .003 is a problem in getting the precision I'm after. The best solution I've found for this is sorting my bullets BTO by using a comparator insert that has the same contact point as my seating stem. This way my seating depths are consistent, though the CBTO, as measured by my standard comparator insert, is not, which is not near as important as having the consistent seating depth. That is to say, having .003, or whatever, variation in distance to the lands is not as important as .003 variation in seating depth. . . as we often make out in OCW testing.
There can be significant difference between the bullet's meplat and the seating stem contact point too. If one is going to tip bullets, I'd certainly want to sort by bullet lengths . . . but then, sort again as I do to get consistent seating depths.
Sorting this way has made a nice difference, even for someone like me who does not use a high end gun, where my groups are mostly in .3 MOA size. I think that's about as good as I can get out of a factory gun with a good barrel (like Krieger).
Dusty Stevens
Shiner
Sort them to OAL and go shoot
Thanks to all for the help. I am just a mid 190's shooter and the rifle is not a high-end custom. A garage built rig with a Big Horn action on a KRG chassis with a Shilen barrel. I will load 20 or 30 rounds with a plus or minus .001 and another 20 or 30 with varying spreads and just have some fun next range session over the chrono and just see what happens
Just a quick update. I compared these blems to 25 Nosler Custom Competitions which is my normal practice bullet. Other than a few discolorations on some of the jackets they are identical. While I did not do a BTO sorting on the Noslers I did a weight check on both the Noslers and the blems. Both the blems and the Noslers had weight differences up to .2 grains measured on my A&D 120. On the blems the I could find no correlation with the BTO length measurement. The Nosler CC's were part of a group buy my club does with Nosler each year. Midway currently sells the 250 ct box for $135.99, I bought the blems from Midsouth for $ 59.99 per 250, a little under 50% of the non blem bullets
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.