Bullet sorting - let us count the ways........

[Killshot]

Match Shooters : what's your process ?
(not theory, mind you, let's keep this short :) on bullet sorting?

By the leading edge of the bearing surface to the base?

The actual bearing surface length using two comparators?
(talking boat-tails here)

And do you sort by one of those bearing surface measurements only, or do also sort further by weight from those lots of equal bearing surfaces?

And no, this won't be an indicator of your O.C.D. ....

 

[DennisH]

Bearing surface with a Sinclair gauge. Exact bearing surface only.

That's it.

 

[mao0720]

The only bullet I sort is the Lapua D46 because I was having issues with consistent seating depth. I sort by bearing surface using two comparators on my calipers. Sort into groups of .002 bearing surface.

 

[benjamin199]

The only sorting I do is by base to tip. I use a whidden pointing die and want all my bullets tips to be pointed the same amount.

 

[johara1]

Sort with a modified Tubb BSC. +- .0005,then trim with a Hoover trimmer and point this takes care of the different overall length issue. and do not mix lot#........jim

 

[Steve3]

Dennis - What Sinclair gauge do you use?

 

[thumper4fun]

Since I shoot boat-tail bullets I'm going to use 2 Hornady comparators with 6mm inserts (link to example below) to measure and sort by bearing surface.

http://www.midwayusa.com/product/231904/hornady-lock-n-load-bullet-comparator-basic-set-with-6-inserts

 

[Cigarcop]

I could care less about the bearing surface personally. The only spot that interests me is the point on the bullet that makes contact with the lands. I measure this using Bob Greens Bullet Comparator and all my ammo measures exactly the same when the bullets are seated base to lands.
What are you accomplishing measuring the bearing surface of a bullet that will help you when seating it to a desired measurement?

 

[kyreloader]

From another thread, here is how Bryan Litz feels about it.

FWIW, in the process of doing more digging, I found some more information in Sinclair International's Reloading Blog, this time citing Bryan Litz as the source:

Another question arose about base to ogive sorting, and if sorting by bullet bearing surface (boat-tail junction “pressure ring, or heel” to ogive with the use of two comparators) was more critical in terminal performance of the bullet. I spoke with Bryan Litz, author of “Applied Ballistics for Long range Shooting”, and lead ballistician for Berger Bullets. Bryan informed me that the most critical measurement in bullet sorting for consistency is in fact the base to ogive measurement. According to Litz, this measurement is in fact sorting the bullets for consistent Ballistic Coefficients (BC). What occurs in the bullet forming process is what determines the bullets physical ballistic qualities. When a bullet is forced into the forming die a few factors come in to place to determine the outcome. These factors include the amount of lubrication used and how it can change the force exerted on the bullet when being formed. If the bullet is forced further than it should into the die, the outcome is a bullet with a short bearing surface, long ogive, and narrow meplat. If not forced far enough, the result is the opposite, long bearing surface, short ogive, and wide meplat. This is why variations are found in bullets, and by sorting them by the base to ogive you are sorting by the best method available. Measuring the bearing surface makes sense, but Litz has found through experimentation more inconsistent results with this method. He explained that if you look at the pressure ring of a bullet under magnification there are inconsistencies that resemble a wavy line. The heel of a bullet is not a repeatable surface like the bullet’s ogive, and these inconsistencies will cause varied measurements. Most would think that the bearing surface variants of a bullets would affect velocity spreads, but Litz claims that that factor is “down on the list”, and in tests showed little if any effect.

I guess that pretty much answers my question...

 

[ovenpaa]

For me the process is:

Sort by weight.
Sort by bearing surface length
Sort by base to upper edge of bearing surface.

My measurements of the bearing surface are actually at the closest point to the bearing surface as the closer you get to the .3080" point the more the form from bearing surface to Ogive or Boat tail tends to blend in and error can creep in so I choose to measure at the point the bullet would typically engrave the lands. Also to overcome the issue of parallax I use comparators that key together when fitted into the callipers so I know they are correctly aligned, this also gives repeatability to the resolution of the callipers if the comparators are removed and then fitted again. Typically the same bullet measured 10 times should never vary by more than .0005" on the calliper and such variation is usually down to the pressure exerted on the bullet and the limitations of the callipers. I only use good callipers as the jaws of the cheaper ones are often bowed very slightly which leads to errors.

I do have a system that fits onto a micrometer which measures to .00005” however it is slow to use and the advantages are debatable when you consider thermal expansion of the bullets in varying ambient temperatures.



 

[Steve Blair]

I could care less about the bearing surface personally. The only spot that interests me is the point on the bullet that makes contact with the lands. I measure this using Bob Greens Bullet Comparator and all my ammo measures exactly the same when the bullets are seated base to lands.
What are you accomplishing measuring the bearing surface of a bullet that will help you when seating it to a desired measurement?

[br]
+1

 

[johara1]

Sorting by bearing surface has to do with eliminating vertical. Seating has nothing to do with any of this,I made a tool from an old Tubb bearing surface comparator and now i can hold less than .0005 in seating length. Checking with a vernier is subject to feel,and if you look at it you can make it any measurement you want. with the tool i made,it uses a dial indicator tension,the same every time now....... jim

 

[thumper4fun]

The OP asked about bullet sorting, not loaded round sorting. But since you brought it up I also measure my loaded rounds to ensure proper and consistent seating depth.

I could care less about the bearing surface personally. The only spot that interests me is the point on the bullet that makes contact with the lands. I measure this using Bob Greens Bullet Comparator and all my ammo measures exactly the same when the bullets are seated base to lands.
What are you accomplishing measuring the bearing surface of a bullet that will help you when seating it to a desired measurement?

 

[Steve Blair]

The OP asked about bullet sorting, not loaded round sorting. But since you brought it up I also measure my loaded rounds to ensure proper and consistent seating depth.

I could care less about the bearing surface personally. The only spot that interests me is the point on the bullet that makes contact with the lands. I measure this using Bob Greens Bullet Comparator and all my ammo measures exactly the same when the bullets are seated base to lands.
What are you accomplishing measuring the bearing surface of a bullet that will help you when seating it to a desired measurement?

[br]
Cigarcop wrote that he used Bob Green's tool to sort bullets. The end result is that seating depth is consistent within ±.001".

 

[thumper4fun]

Cigarcop wrote that he used Bob Green's tool to sort bullets. The end result is that seating depth is consistent within ±.001".

And that is excellent but if the bullet bearing surface extreme spread is .030 between rounds does that ±.001 seating depth really matter? I prefer to have my bullets sorted by bearing surface and then seated to ±.001.

 

[Steve Blair]

Cigarcop wrote that he used Bob Green's tool to sort bullets. The end result is that seating depth is consistent within ±.001".

And that is excellent but if the bullet bearing surface extreme spread is .030 between rounds does that ±.001 seating depth really matter? I prefer to have my bullets sorted by bearing surface and then seated to ±.001.

[br]
You do whatever you find works for you. I found no value when sorting by bearing surface. For the record, never found anywhere near .030" variance. And, yes, seating depth variance does matter. [br]
Do you compete in some discipline?

 

[mikegaiz]

Like johara1 said? Bearing surface variances changes bullet resistance and therefore velocity. That's apples and cumquats ???

 

[johara1]

Steve, I think the difference is the discipline, I shoot 1k BR. and the need for more accuracy than X corse or F class. I can see the difference from Bearing surface sorting and trimming and pointing for consistency for the year. Get the seating depth consistent is important also. vertical is well under your X ring for all year..... jim

 

[thumper4fun]

You do whatever you find works for you. I found no value when sorting by bearing surface. For the record, never found anywhere near .030" variance. And, yes, seating depth variance does matter. [br]
Do you compete in some discipline?

I compete in both short range and long range (500-600 yd) bench rest. I don't do any kind of bullet sorting on my short range bullets.

And at what point did I say seating depth doesn't matter? What I did say is that IMHO having ±.001 seating depth may not matter as much if there is a .030 extreme spread in the bullet bearing surface between rounds. (By the way I have measured .030 of extreme bearing surface spread in bullets from the same box of 500 and that's why I continue to measure the bearing surface.) I also don't think having a ±.001 seating depth will matter that much if the extreme spread of your powder charges are ± .2 gr from round to round. That's why I hand weigh each powder charge individually.

But the OP didn't ask about seating depth or weighing charges, he asked about methods for bullet sorting and that's what I provided.

 

[johara1]

I have saw 107's that were well over .060 in the bearing surface length a box of 100 and 108's from an other mfg. more than that with 30 cal. bullets mixed in to boot..... I think these are the one's they shovel off the floor...... jim