Bullet sorting options?? (Brian?)

[vanwhyjr]

Question to all the experts.

I have the capability to measure every feature of a projectile to around ~.0003" accuracy. Including run out of ogive, run out of boat tail, roundness of the body, overall length, length to theoretical barrel bore, and weight to the .000 in grains.

What dimension would you think was the most critical to sort with?

Here is what I would be using for the dimensional numbers. http://www.jenoptik.com/Internet_EN_HOMMEL-ETAMIC_opticline_C800

Wondering if Brian has any comments?

Thanks,
Frank

 

[Bryan Litz Ballistics]

For uniformity in BC, focus on the tip/meplat.

It's very difficult to measure the diameter of a meplat with normal instruments (calipers). Of all the dimensions on a bullet that effect the shot-to-shot BC consistency, meplat is the big one.

Even with that expensive machine, I'm not sure how you would characterize the size of the meplat since it's not a perfect circle, but this is where to look.

As for other bullet dimensions that may be related to precision (group size), it's a good question. If the machine has the ability to scan many dimensions quickly, I would suggest dumping the bullets thru it, have it scan many dimensions and kick out the bullets that are outliers in any dimension. Note which dimension was out, mark the bullet, shoot it in a group and observe the impact. In this way you can determine which dimensions matter, and can report back to us, HA!

What you'll find is that many of the bullet dimensions correlate. For example, smaller meplat's are consistent with longer noses, which correlates to shorter BTO. Those are all the symptoms of a bullet that's pointed up more than others. On the contrary, a bullet that isn't pointed up as much will have a wider meplat, shorter nose, and longer BTO (more bearing surface). For well made bullets, the variations are typically slight (I think it's caused by some bullets having more or less lube in the point swaging process) and the effect on BC would be minor.

Take care,
-Bryan

 

[vanwhyjr]

I see this turning into a big project! LOL

I will try to measure a box of 500 and see the standard deviations of all the measurements and try to set the outliers aside. From what i've seen on some 10 pcs samples the outliers are a rare occurrence! Which is a good thing.

vanwhyjr

 

[R.Morehouse]

If you like playing with measuring and sorting bullets a lot see if you can find yourself an original in perfect working order Vern Juenke machine......

 

[vanwhyjr]

That's a cool machine!

we have had stuff cat scanned and x-rayed to see jacket thickness but only in one place. It wouldn't tell you an internal concentricity.

Might have to talk to the money guys !!!

 

[dreever]

I used to do all that crap. Boxes and boxes of little piles of bullets. Then trim and point and sort some more. Drove me crazy.
Now I just shoot Berger's right out of the box. To each his own.

Danny

 

[vanwhyjr]

I used to do all that crap. Boxes and boxes of little piles of bullets. Then trim and point and sort some more. Drove me crazy.
Now I just shoot Berger's right out of the box. To each his own.

Danny

Yeah that's what I do now. Been shooting pretty well so far. I was just thinking what difference it would make. I don't know if its worth 1 or 2 points or 10.

 

[Canadian bushman]

We use oasis optical measuring computers where i work and they stuggled greatly with measuring the bullet as close as i thought they would.

Extrapolating a radius dim as well as endpoints on such a small section of such a large radius ( that intersects with other radii ) threw it for loops. Even our zeiss cmm struggled. I think expecting .0003" consistency may be wishfull. I was looking at around .002-.005"

I resorted back to my previous means.

 

[vanwhyjr]

We use oasis optical measuring computers where i work and they stuggled greatly with measuring the bullet as close as i thought they would.

Extrapolating a radius dim as well as endpoints on such a small section of such a large radius ( that intersects with other radii ) threw it for loops. Even our zeiss cmm struggled. I think expecting .0003" consistency may be wishfull. I was looking at around .002-.005"

I resorted back to my previous means.

Yeah the ogive radius is such a small degree of an arc most software based equipment struggles. I measured 54 bullets and that dimension had the largest variation. I have the data on my work computer. I can post it when I get back to work Thursday. The SD numbers were pretty impressive.

 

[Quickoz]

Ive taken to measuring bullet OAL as that should be the biggest influence in BC I would think. But thats with 180gr VLD and the meplats are a tad inconsistent but I also havent seen much difference between nybsorted and unsorted groups.

 

[Marksman63]

I have a question for the experts.
Business case: Berger 200 Hybrid for F TR pushed at 2780 fps

Currently I have a Montour meplat trimmer but still need buying a pointing die. What is best?
1. Use bullets out of the box;
2. Sort bullets according BTO measurements;
3. Uniform bullet's meplats accepting a small BC reduction;
4. Both 2. and 3.

Thanks
Amleto

 

[memilanuk]

I have a question for the experts.
Business case: Berger 200 Hybrid for F TR pushed at 2780 fps

What I want to know is HTF are you getting them going that fast out of a .308?!?

Currently I have a Montour meplat trimmer but still need buying a pointing die. What is best?
1. Use bullets out of the box;
2. Sort bullets according BTO measurements;
3. Uniform bullet's meplats accepting a small BC reduction;
4. Both 2. and 3.

For your sanity, option 1.

Until you are in the top 3-5 at well-attended Regional or National events, option 1 is probably the most productive use of your time and resources.

If you still really really want to do something to your bullets, I'd suggest sorting by overall length (vs. base-to-ogive) before trimming, followed by pointing. The reason I say sort (actually batch) by length is that I've found that even with good quality bullets i.e. Berger, while the BTO may be very consistent - to within a few thousandths per lot (making it largely ineffective as a sorting criterion) - the OAL may vary more widely. To use numbers that I have close at hand for B185OTMs (vs 200 hybrids, sorry), I saw a majority between 1.358-1.367". Actually, I binned just that section into two or three batches. Then the 'tails' of 1.357" and below, and 1.368" and above - some all the way down to 1.350", and some up to 1.377". Sticking the shorter bullets in a trimmer set for the median results in little or nothing being taken off. Sticking a longer one in results in a huge meplat. The result is *increased* inconsistency, which is contrary to the goal here. Similarly, sticking a short (untrimmed) bullet in a pointing die set for the median results in not much if anything being done. Sticking a long (untrimmed) bullet in the same die results in the tip being smashed together, and possibly even setting back or buckling the boat tail (seen people do it). Along the same lines, pointing up bullets that have all been run thru the trimmer regardless of length can result in better, but still varying meplats - if you think a bullet that was 1.352" to begin with and didn't touch the trimmer, and one that started off 1.375" and now looks like a flat-nose wadcutter are going to point up the same, I've got news for you - NO. But taking ones that are binned together with small batches, so they get roughly the same amount trimmed off, should result in bullets that point up the same - and without risking any setback or buckling. Use the bullets in the 'tails' for load development, foulers, sighters, etc. The difference won't be *that* much different that you can't get good wind dope off of them, for example.

Or you could just skip all this and go with option 1. I'm pretty sure I drop way more points to bad wind calls than I do to my bullets meplats. I understand wanting to do it for the mental safety blanket of knowing you've done everything possible, but be aware its not even remotely close to being the biggest source of error for most people.

YMMV,

Monte

 

[jsthntn247]

I sort bullets (1000 at a time) by base to tip in .001 increments. I'll have about 12 different piles. I then point each pile, resetting the die for each pile and comparing the meplat openings to the previous pointed piles so that they all look identical. I'll have enough in each pile to shoot a match or three with bullets that are all within .001 in total length with identical looking meplats. I shoot the same scores at mid range as I did before I wen through all the trouble because of missed wind calls or improper rifle handling/cheech pressure, grip torque...etc.

 

[Marksman63]

I have a question for the experts.
Business case: Berger 200 Hybrid for F TR pushed at 2780 fps

What I want to know is HTF are you getting them going that fast out of a .308?!?

Thanks for your comprehensive explanation
My receipe is a Benchmark 32" 1/10 barrel, RS52 powder and Lapua Palma cases. My tests almost confirm QL results and pressure is around 63kpsi
Currently I have a Montour meplat trimmer but still need buying a pointing die. What is best?
1. Use bullets out of the box;
2. Sort bullets according BTO measurements;
3. Uniform bullet's meplats accepting a small BC reduction;
4. Both 2. and 3.

For your sanity, option 1.

Until you are in the top 3-5 at well-attended Regional or National events, option 1 is probably the most productive use of your time and resources.

If you still really really want to do something to your bullets, I'd suggest sorting by overall length (vs. base-to-ogive) before trimming, followed by pointing. The reason I say sort (actually batch) by length is that I've found that even with good quality bullets i.e. Berger, while the BTO may be very consistent - to within a few thousandths per lot (making it largely ineffective as a sorting criterion) - the OAL may vary more widely. To use numbers that I have close at hand for B185OTMs (vs 200 hybrids, sorry), I saw a majority between 1.358-1.367". Actually, I binned just that section into two or three batches. Then the 'tails' of 1.357" and below, and 1.368" and above - some all the way down to 1.350", and some up to 1.377". Sticking the shorter bullets in a trimmer set for the median results in little or nothing being taken off. Sticking a longer one in results in a huge meplat. The result is *increased* inconsistency, which is contrary to the goal here. Similarly, sticking a short (untrimmed) bullet in a pointing die set for the median results in not much if anything being done. Sticking a long (untrimmed) bullet in the same die results in the tip being smashed together, and possibly even setting back or buckling the boat tail (seen people do it). Along the same lines, pointing up bullets that have all been run thru the trimmer regardless of length can result in better, but still varying meplats - if you think a bullet that was 1.352" to begin with and didn't touch the trimmer, and one that started off 1.375" and now looks like a flat-nose wadcutter are going to point up the same, I've got news for you - NO. But taking ones that are binned together with small batches, so they get roughly the same amount trimmed off, should result in bullets that point up the same - and without risking any setback or buckling. Use the bullets in the 'tails' for load development, foulers, sighters, etc. The difference won't be *that* much different that you can't get good wind dope off of them, for example.

Or you could just skip all this and go with option 1. I'm pretty sure I drop way more points to bad wind calls than I do to my bullets meplats. I understand wanting to do it for the mental safety blanket of knowing you've done everything possible, but be aware its not even remotely close to being the biggest source of error for most people.

YMMV,

Monte

 

[mikecr]

OAL is even less meaningful than BTO..
The Montour meplat trimmer(excellent) takes datum off the ogive, and neither BTO nor OAL mean anything about nose length itself. Same would apply to pointing with a Hoover(again excellent).

You need to pay mind to meplat diameters and what it takes to make them the same.

 

[Joe Salt]

I'm with jsthntn427, But I'll give you something else to think about! I got a Lot # of Burgers bullets that go through my .309 bushings but the ones I have now will only go though the one bushing. So my Question is how far can you go in Dia. before the lands distort the lead in the bullet and you start getting flyers?

Joe Salt

 

[vanwhyjr]

So here is a spreadsheet with the measurement results on 54 Berger 140gr Hybrid 6.5mm projectiles from Lot #6204.

How would you guys sort with this info?

Vanwhy