Bullet sorting - bearing length

[LongBomber]

Was sitting around this afternoon so I broke out the calipers and went to work on a few boxes of bullets. Setup with two hornady comparators so measuring is simple and quick. Ran through a box of each all 6.5mm - 143eldx, 147eldm, 130 game changer, 129 and 142 lrab. My actual measurement number is only based off my two inserts so basically meaningless but the variation in bearing length was interesting. I broke out some sorted bullets to test groups and es later.

143eldx 90 bullets fell within .003" window, then 6 were .008" shorter than the average, 3 were .005" longer than average. One zinger that was .012" longer.

147eldm similar to the 143's, only had 70 bullets. 68 were within .003" two were .007" longer. Both of the 143/147 measured out much better than the 338" 230's I measured, those varied as much as .020" with very few around an average length.

130 game changer's- these definitely mix two production lines in a box. Broke the seal on a box of 100. I had two distinct length groups that were .007" apart. But all the bullets fell within .001" of a length "node". Very consistent but definitely mixed production.

129lrab 60 bullets - 59 fell within a .004" range. But one bullet was a full .021" short of the average.

142 lrab - 96 fell within .007", I split them into two groups for doing some testing. Four bullets were .010" short of the average.

I was impressed with the consistency of the hornady, thats the best I have measured from them.

The game changers were a bit of a disappointment, I think to get the best from them length sorting is definetly needed. I haven't shot any of these yet so I am going to do some testing with each length and with a mixed batch, see what the paper says.

 

[elkaholic]

Was sitting around this afternoon so I broke out the calipers and went to work on a few boxes of bullets. Setup with two hornady comparators so measuring is simple and quick. Ran through a box of each all 6.5mm - 143eldx, 147eldm, 130 game changer, 129 and 142 lrab. My actual measurement number is only based off my two inserts so basically meaningless but the variation in bearing length was interesting. I broke out some sorted bullets to test groups and es later.

143eldx 90 bullets fell within .003" window, then 6 were .008" shorter than the average, 3 were .005" longer than average. One zinger that was .012" longer.

147eldm similar to the 143's, only had 70 bullets. 68 were within .003" two were .007" longer. Both of the 143/147 measured out much better than the 338" 230's I measured, those varied as much as .020" with very few around an average length.

130 game changer's- these definitely mix two production lines in a box. Broke the seal on a box of 100. I had two distinct length groups that were .007" apart. But all the bullets fell within .001" of a length "node". Very consistent but definitely mixed production.

129lrab 60 bullets - 59 fell within a .004" range. But one bullet was a full .021" short of the average.

142 lrab - 96 fell within .007", I split them into two groups for doing some testing. Four bullets were .010" short of the average.

I was impressed with the consistency of the hornady, thats the best I have measured from them.

The game changers were a bit of a disappointment, I think to get the best from them length sorting is definetly needed. I haven't shot any of these yet so I am going to do some testing with each length and with a mixed batch, see what the paper says.

Thanks for doing that test. It definitely shows one of the reasons that you can get a flier out of an otherwise great shooting load!

 

[LongBomber]

What length tollerance does a person sort to?
I normally just eliminate the real outliers and use the main group of bullets. But would it be better to group into say .002" length groups?

 

[Mikecr]

Only shooting will tell if any of this effort matters.
Let us know

 

[Calvin45]

I appreciate your research, makes a heck of a lot more sense than measuring projectile overall length, at least from an internal ballistics perspective. Bearing surface variations = pressure variations.

 

[Rhovee]

Overall length gives difference in BC. Always looking for that one that's going to screw you up.

 

[kiwikid]

Is this actually measuring the bearing length or could the measurement also be influenced by the diameter of the bullet where it sits in the comparator?

 

[LongBomber]

Is this actually measuring the bearing length or could the measurement also be influenced by the diameter of the bullet where it sits in the comparator?

It could influeneced by the dia where it enters the comparator, but that is still likely more accurate than trying to just line up calipers on the bullet. At least with the tools I have.

I would like to get a couple custom inserts made up, doing your own inserts you could match them to the barrel land dia of a specific barrel and cut in the correct lead angle. That would allow the closest match to your chamber. Of course that only matters on the ogive, not on the boat tail since there is nothing to match that up to.

 

[LongBomber]

Only shooting will tell if any of this effort matters.
Let us know

Going to be a while before I get out shooting again. Was at the gym Friday doing my back routine and dislocated the left side si joint, slipped the L1 disk and a muscle tear on something I can't pronounce. So far the docs are not thinking surgery, but it sure is not ideal.

I have run similar tests on 140 berger vld's in my 260ai before, it really didnt do much to the es/sd of the load but it did reduce the flyers. I am forming the opinion that you really just need to pull out the odd-ball bullets in weight/bearing surface length to make a reduction in the fliers. Seems like common sense.

 

[Mikecr]

Seems like common sense.

This isn't common sense. It's science. Avoid conformation bias.

 

[epags]

Going to be a while before I get out shooting again. Was at the gym Friday doing my back routine and dislocated the left side si joint, slipped the L1 disk and a muscle tear on something I can't pronounce. So far the docs are not thinking surgery, but it sure is not ideal.

I have run similar tests on 140 berger vld's in my 260ai before, it really didnt do much to the es/sd of the load but it did reduce the flyers. I am forming the opinion that you really just need to pull out the odd-ball bullets in weight/bearing surface length to make a reduction in the fliers. Seems like common sense.

Well it has been almost a year. Hope your back has recovered and you have been able to go shooting again.
Did you ever complete your testing of accuracy vs bullet variation?

I was performing the same measurement comparison today and decided to do a search on LRH to see if others had also.

Background:
I have a container of 145 gr SPBT Speers I bought 100+/- years ago when the price was $6.21 for 500.
Without any comparator checking before loading to try a jump test, my Rem 700 (factory) found two adjacent nodes that gave a 3/4 MOA using Reloader 22 @ 66 grains. I am about to use the average of the two jumps (.085) and search for the best powder weight.

 

[LongBomber]

I need to sit down and go through some groups and put the information together. Sorting by bearing length and weight has definitely reduced the fliers. It also reduced the vertical spread at 1000, although that may also be part of the reduction in fliers, consistency never hurts. Sorting by either weight or bearing length individually also seems to help but I was still seeing the odd shot where you asked yourself "how did that one go there??" With either method.

I think the basic quality of the bullet matters as well. I had a couple boxes of 338 230gr eld's they were not great, over 0.020" difference in bearing surface length was common and over 2gr of weight difference. They definitely mix production lines as I had two "nodes" that were roughly 1.5gr apart in weight and .010" apart in bearing surface length. But I just sorted 300 berger 144hyb and the grain spread was 0.4gr and the bearing surface was all within 0.005" for all bullets except 1. That bullet was out 1.5gr and had a slightly deformed tip. Really sorting will make next to no difference on those.

The one thing that did not seem to improve much was the es/sd of the load. If 20 shots unsorted was an es of 20 sd of 6 then sorted may have been 19/5, but you would need hundreds of shots to make that a valid result. Either I have something else in the process that is contributing to the es/sd in a larger way or sorting bullets really doesn't change the es/sd.