CBTO, COAL, concentricity. relate how?

[goodgorilla]

I'll just define them first to make sure I got them right.
CBTO - cartridge base to ogive
COAL - cartridge overall length
concentricity - the consistency of the ogive surface.

How do I respect all three? Do you try to sort out cartridges that are most similar in all 3? Pull and throw out the freak bullets?

 

[Aimsmall55]

You measure to the ogive when loading because that's what is going to contact your rifling first and metplates vary on length. So instead , for example, I'm loading to 2.236 to the ogive on a 175 smk , the COAL will vary probably 5 to 10/1000's off of 2.820". I use a hornady comparator for the job. As far as your question about the throwing away bullets.... Why would you do that. If its the same lot, you may have some very a little but I personally wouldn't toss anything.
Take a little advice... Quit being so OCD and enjoy.

 

[goodgorilla]

You measure to the ogive when loading because that's what is going to contact your rifling first and metplates vary on length. So instead , for example, I'm loading to 2.236 to the ogive on a 175 smk , the COAL will vary probably 5 to 10/1000's off of 2.820". I use a hornady comparator for the job. As far as your question about the throwing away bullets.... Why would you do that. If its the same lot, you may have some very a little but I personally wouldn't toss anything.
Take a little advice... Quit being so OCD and enjoy.

My rifle isn't going to be done for several months so all I can do is read and write about this stuff. I do have most of the tools though.

 

[Aimsmall55]

My rifle isn't going to be done for several months so all I can do is read and write about this stuff. I do have most of the tools though.

10-4. Go to the stickys and read all those articles. Alot of good stuff in there. Also get some reloading manuals ( BERGER is a good one ) and you'll learn a good bit about your question.

 

[goodgorilla]

10-4. Go to the stickys and read all those articles. Alot of good stuff in there. Also get some reloading manuals ( BERGER is a good one ) and you'll learn a good bit about your question.

I've just read that section of the berger manual for the 3rd time or so. The manual is sitting next to me, reading the stickies sounds like a good idea.

 

[oldfudd]

I'm still learning, but would like to point out that "concentricity" is not just the consistency of the diameter at the ogive of the projectile, but is the runout variance of the projectile when seated in a loaded case. It is my understanding that concentricity gives you some insight with regard to the centerline axis of the loaded projectile in the case relative to the centerline axis of the case/chamber. The more the two axis are aligned, the more consistent the projectile's flight will be to others. As my wife would put it "if the bullet is wonky, it will have a tendency to rattle down the bore".