CBTO

[Rflshootr]

Marked for size likely, marked for which side to use? No idea.

That will work!

BUT, to my original point that is only good within your set of tools. For instance say you have a rifle built and the builder finds some recommended load(s) for it. Their CBTO number(s) will mean nothing to your tools. If a standard is developed then their numbers will mean something to your tools because they're all conforming to that standard. OR say that your reloading skills are now up to speed and you want to take over the loading that a friend has been doing. Same thing, his tools are different and his CBTO numbers are useless to you. In both cases you'll need to measure with your tools and record your measurements. It's not the end of the world to do this, but wouldn't be beneficial if you didn't have to? Imagine a world where no one's scale weighs the same. This is a similar thing.

Exactly! It's just a reference number that YOU generate with your particular gauge and the lot of bullets that you are using for YOUR rifle. It means absolutely nothing to anyone else.

 

[L.Sherm]

First of all last time I checked this was a LONG RANGE FORUM and if you not interested in it why even be here.
As to different methods it all boils down to consistency whatever you do.
If you wonder about the way bushing should be used all manufacturers have a recommended way , Whidden has an arrow and Redding says stamp down
Alot of things like this theres times you won't see differences at 100 but I guarantee you it shows up big time at 500 and beyond. Its like Alex Wheeler and others always say test for yourself and believe the target.
Yes tolerances stack up its why I make sure my bump is no more difference than 1/2 thou and my seating CBT0 same thing. Hardness of brass effects it, brass prep especially the neck area,seating stem contact.etc.

 

[ntsqd]

Exactly! It's just a reference number that YOU generate with your particular gauge and the lot of bullets that you are using for YOUR rifle. It means absolutely nothing to anyone else.

Until you need to transfer that information to someone else. Say you sell that rifle to a friend. Now what?

Like I said at the beginning, maybe it's worth consideration and maybe not. To some it won't matter at all. To others it may.

 

[bamban]

Do you have any idea what you just started???

He is probably enjoying his coffee, beer, wine or whiskey at different times of the day just laughing at the chit storm he created.....lol

 

[C-130 Dude]

Marked for size likely, marked for which side to use? No idea.

That will work!

BUT, to my original point that is only good within your set of tools. For instance say you have a rifle built and the builder finds some recommended load(s) for it. Their CBTO number(s) will mean nothing to your tools. If a standard is developed then their numbers will mean something to your tools because they're all conforming to that standard. OR say that your reloading skills are now up to speed and you want to take over the loading that a friend has been doing. Same thing, his tools are different and his CBTO numbers are useless to you. In both cases you'll need to measure with your tools and record your measurements. It's not the end of the world to do this, but wouldn't be beneficial if you didn't have to? Imagine a world where no one's scale weighs the same. This is a similar thing.

The instructions at Whiddens site say to hold the bushing up. Read the print on the bushing and drop it into the die. Do not flip it over.

 

[Shane Lindsey]

If you use your comparator on bullets from some bullet manufacturers, I won't name names but it starts with an H and ends with an ornady, doesn't have a consistent base to ogive distance. So, every bullet seated, with no change to the seating die, varies. a few thousandths in length.

To be fair the bullet I measured is a hunting bullet and most people just seat, dump, and squash when they load those. Most people as in new reloaders and "less picky" reloaders <-- is that even a thing?

Yupp...that is why no pills that rhyme with horny or not today are on my bench.

 

[QuietTexan]

If you use your comparator on bullets from some bullet manufacturers, I won't name names but it starts with an H and ends with an ornady, doesn't have a consistent base to ogive distance.

Guess you also have to list Barnes, Sierra, Nosler, Berger, and every other manufacturer of cup and core bullets out there that aren't 100% hand pressed.

Sierra commonly runs two lengths per box, they must mix machine output into the wash. Barnes Match Burners have a much wider dispersion of lengths per box than Hornady. I sorted 500x Hornady 140 Match HPBTs and ended up with 4 groups, compare that to Berger 300 OTMs that ended up in 3 different sorted lots.

Hornady A-Tips are packed sequentially and unwashed to avoid this issue, so they're better than the average Big Red.

Vapor Trail machine pressed are the best I've sorted, to the point that I gave up. 2k bullet lot, has been great so far.

And that's the real question - does any of this actually show up on the target? 338 Light Class ELR yes, 1000 yard F-Class maybe, 600 yard ultralight hunting rifle no, 100 yard paper punching not on your life

Litz put an entire chapter on bullet sorting into his newest Vol III book, he did all the math and it boils down to bullet length is more representative of ALL the dimensional errors in a bullet, to include base to minor bore diameter (what most here call BTO), overall length, boattail length, bearing surface length, and meplat tip. It was a very interesting read, and since I had the 500x of Hornady bullets still sorted I was able to confirm that length varied pretty consistently between the 3 groups I sorted out, and didn't vary much inside a group.

 

[ntsqd]

The instructions at Whiddens site say to hold the bushing up. Read the print on the bushing and drop it into the die. Do not flip it over.

Up or down doesn't matter to consistency as long as it's always done the same way, but might it matter due to how the bushing was made.

 

[Old Rooster]

This thread has me thinking.
I just bought a box,bag of Nosler Accubond (seconds) and the seconds part may have something to do with varying degree's of Bullet Base To Ogive.I'll measure them just to find out.Will take a while but I am determined to do it to see just why they are called seconds.

 

[C-130 Dude]

Up or down doesn't matter to consistency as long as it's always done the same way, but might it matter due to how the bushing was made.

It does.

 

[ntsqd]

I suspected as much.

 

[Rflshootr]

Until you need to transfer that information to someone else. Say you sell that rifle to a friend. Now what?

Like I said at the beginning, maybe it's worth consideration and maybe not. To some it won't matter at all. To others it may.

Then send a dummy round and the bullet specifics with the rifle and let them take their own measurements with their equipment and get their own reference number. I use a Sinclair nut gauge. It will absolutely not give the same measurement as Whidden or Hornady equipment.

SINCLAIR HEX STYLE BULLET COMPARATORS | Brownells

We have been making these hex style bullet comparators for over 20 years, and believe we make the most accurate tools available. The holes in the Sinclair Bullet Comparators are cut with throating reamers to accurately duplicate the actual throat ...

www.brownells.com

 

[QuietTexan]

Until you need to transfer that information to someone else. Say you sell that rifle to a friend. Now what?

Have him measure a loaded round with his tools, and he has his number. The tools (excepting SAC) aren't accurate enough to be more than comparators.

 

[Muddyboots]

This thread has me thinking.
I just bought a box,bag of Nosler Accubond (seconds) and the seconds part may have something to do with varying degree's of Bullet Base To Ogive.I'll measure them just to find out.Will take a while but I am determined to do it to see just why they are called seconds.

Even their new ones have variances that will surprise you.