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How to measure,base to ojive, and is BTO, more important than .1 of a grain for sorting bullets 108s

NC/Br Shooter

Silver $$ Contributor
I don't have anyone to teach me this stuff, except y'all Iv been to a few matches. Put together a dozen or more Br rigs. I read on here. It's certainly an addiction. I guess it's a good one though.
Sorting bullets!
I'm sorting Berger 108s. In this picture, Is this the correct way to measure base to ojive?
If it is ,will work this way? , Is this more important than say a .1 of a grain difference in bullet weight?
I started measuring some and right away I started seeing a variance.
I seat my bullets in a away I try and get the ojive of the bullet say .010 from lands. But Iv noticed when I set my die I still get a variation. I'm hoping this will go away if I sort.
 

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Yes that is base to ogive on a bullet.

Sorting based on this can be useful at long range because variances in bullet shape affect ballistics. I would sort on this first before sweating .1 gr weight differences.

For any long range application I recommend weighing all bullets at least to cull the very heavy and light bullets. Shoot the mix of extreme heavy and light bullets as barrel warmers / fire formers sometime to see how much difference that makes for you. Sorting will of course have even less effect.

The deeper cause why this matters is because the shape of the bullet around the ogive needs to be extremely consistent to fly with consistent ballistic coefficient. while base to ogive doesn’t directly measure variances in shape, it tends to catch the bullets that aren’t like the others. There are special tools that measure the distance between two ogives simultaneously and those seem to be a more direct way to see it. But to get started I think you’ll either 1) prove it does or does not affect your accuracy on target with these bullets and 2) give you a sense of how consistent your lot of bullets is.
 
22bra4350 said:
I don't have anyone to teach me this stuff, except y'all Iv been to a few matches. Put together a dozen or more Br rigs. I read on here. It's certainly an addiction. I guess it's a good one though.
Sorting bullets!
I'm sorting Berger 108s. In this picture, Is this the correct way to measure base to ojive?
If it is ,will work this way? , Is this more important than say a .1 of a grain difference in bullet weight?
I started measuring some and right away I started seeing a variance.
I seat my bullets in a away I try and get the ojive of the bullet say .010 from lands. But Iv noticed when I set my die I still get a variation. I'm hoping this will go away if I sort.
Click to expand...
The BERGER 108gr EH bullet is a hybrid design. This design makes finding the bullet ogive difficult, if not impossible with standard measuring devices. It is even very difficult to do using an expensive optical comparator. So, your measurement can be one that is in the vicinity of the bullet ogive more often than not. Since the HYBRID bullets exhibit great jump tolerance in most cases this " close measurement" is not a factor. Trying to put the same pressure on the caliper each time you measure for CBTO can help make your measurement more repeatable. And can help identify if the tip of the bullet is contacting the base of the cavity of the bullet seater stem changing the CBTO measurement from cartridge to cartridge. VLD bullet seating stems are recommended for use with the BERGER HYBRID bullets also because of this.
Hope this helps.
 
dgeesaman said:
Yes that is base to ogive on a bullet.

Sorting based on this can be useful at long range because variances in bullet shape affect ballistics. I would sort on this first before sweating .1 gr weight differences.

For any long range application I recommend weighing all bullets at least to cull the very heavy and light bullets. Shoot the mix of extreme heavy and light bullets as barrel warmers / fire formers sometime to see how much difference that makes for you. Sorting will of course have even less effect.

The deeper cause why this matters is because the shape of the bullet around the ogive needs to be extremely consistent to fly with consistent ballistic coefficient. while base to ogive doesn’t directly measure variances in shape, it tends to catch the bullets that aren’t like the others. There are special tools that measure the distance between two ogives simultaneously and those seem to be a more direct way to see it. But to get started I think you’ll either 1) prove it does or does not affect your accuracy on target with these bullets and 2) give you a sense of how consistent your lot of bullets is.
Click to expand...
I'll give this a try then. I didn't think a tenth would affect things near as much as the shape.
Iv measured about 200 bullets before I left the house this morning. I basically made two piles.
There seemed to be about 6 thousandths in the two piles I made thus far. And I mean when I measured one, the dial on the caliper either landed on the .74 or .80. On the dot exactly.
So there's the reason for the two piles.
This other special tool, does it have a name?
Or is it something so specialized a bullet maker would only have? Sounds interesting.
Thanks for posting. Was interesting post
 
Small anecdotal observation. I got 1000 SMK 77's as seconds. My Criteria for sorting was bullet Base to ogive into three grossly different groups. I have shot two of my best ever scores with these bullets and have single digit SD's for 20 shots slow prone..... I will be sorting by BTO again in the future.
 
SPJ said:
Maybe not on your targets and no disrespect to any of your sources but I feel better and still don’t see a downside to sorting production components or consider it a waste of time.
Click to expand...
I couldn't agree more.
Forgive me cuz I've been suckin on my sippy cup...
I use to shoot Berger and during a particular 140 vld sort I noticed .020
variation in 1 100 count box sorting CBTO.
This could be in part to being a novice at sorting at the time.....
Shortly after I purchased 1000 136 scenar L's, and only had a .006 variation with a couple outliers of course. WOW !!! That's a huge difference I thought.
Then I got some Bart's bullets and followed his guidance and started sorting "OAL ONLY" batching in .003 groupings.
So if the relationship of ogive to lands is important as I believe it is you won't see a difference in loaded CBTO more than .001. This I checked on Monday as I loaded a charge weight test using 2 of my sorts.
Bart informed me I wouldn't see any diffence in tune because of bullets being seated +or- .001 in the neck.
Another note BC is affected by length not base to ogive so it only makes sense.
Lord knows I'm not capable of shooting the difference. Are you??
So you see learn to separate the wheat from the chaff, and read between the lines between the various loading variations and the disciplines in which they are applied.
Read it, test it, form your own opinion based on your application from your testing, I'll continue my OAL sorting.
Now my sippy cup is calling me!!
 
22bra4350 said:
I don't have anyone to teach me this stuff, except y'all Iv been to a few matches. Put together a dozen or more Br rigs. I read on here. It's certainly an addiction. I guess it's a good one though.
Sorting bullets!
I'm sorting Berger 108s. In this picture, Is this the correct way to measure base to ojive?
If it is ,will work this way? , Is this more important than say a .1 of a grain difference in bullet weight?
I started measuring some and right away I started seeing a variance.
I seat my bullets in a away I try and get the ojive of the bullet say .010 from lands. But Iv noticed when I set my die I still get a variation. I'm hoping this will go away if I sort.
Click to expand...
After talking to a couple of the best custom bullet producers the consensus is sort bullets by overall length.
It's going down a rabbit hole for sure but sorting, trimming and pointing will provide the most consistent BC.To the question of where it stands on the "most bang for the buck" there are just too many variables (as I am not doing your load testing) for me to even guess.
Now, as to bullet seating variance, my guess is the variance you experience is more likely from differences in neck tension in your brass. Learn to get a "feel" for that variable and you'll be able to sort that ammo to the "sighter side" of the ammo box.
 
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