Do you track jump versus COAL

Sasquatch

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I typically use recipes straight out of the book and don't tweak the cartridge length. From what I've read it's getting into the last few tweaks of a precise load and won't make a big overall difference.

Even so, I have a bullet comparator, and a seating tool to see the distance of the bullet to the lands. With this I can figure out the max length before I get zero jump (or jam if I go negative). This is only appropriate to the bearing surface of the bullet, and each bullet will be shaped differently (having a different COAL).

Do people translate ogive length to coal for loading on each bullet, or do you only use ogive distance?

I also hear that as barrels wear, the throat length will increase- do people track that?
 
For consistent performance in my bolt guns, I do track jump as it increases as the throat is burned out from use. Likewise, I pay more attention to my length to ogive than I do to COAL. I have most bullets from Hornady to be surprisingly consistent with the length to ogive, COAL a little less consistent, but not much.

I don't play with bullet jump until I have settled on an OCW, and then I only play with a couple of 1000ths either way to see if it makes any difference. It usually tightens things up more than you might think. Have gotten a 1/4 MOA out of it before, but have also gotten nothing out of it.
 
I check the lands to ogive length, in a few of my rifles it made little difference. My Sako 75 has such a long lead that setting the bullet 0.010"off the lands made it almost 1/4" longer COAL over factory ammo. The 100 yrd groups went from 2.75" to 0.355".
 
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I go by OAL since the ammo could be used in different guns
 
I'm starting to put down some data of COAL versus jump for my different bullets in my Savage FCP

Example::
168 match, COAL is 2.912 to touch the lands.

@Pink_Vapor
Is 10 thou considered a good jump point, loading to 2.902?
 
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I usually look for 0.02 to 0.04 in. jump unless I am using a VLD bullet, in which case I will start with contact and back off of it out to 0.02. If not improvement, I don't see a reason to go further.

Your 10/1000ths is perhaps a little close, but hey if it works, it works, or you can try moving back another 10/1000ths. By the way, I have found SMKs to vary in bullet overall length by as much as a couple of thousandths, that is one reason I use length to ogive.
 
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Mag length for general purpose. Ogive overall length for target rounds.
 
I'm starting to put down some data of COAL versus jump for my different bullets in my Savage FCP

Example::
168 SMK, COAL is 2.912 to touch the lands.

@Pink_Vapor
Is 10 thou considered a good jump point, loading to 2.902?
- I only play an expert on TV
- "Is 10 thou considered a good jump point", depends on gun and bullet, I'll usually start at 10. Berger VLD's seem to like a lot of jump, my Sako 7-08 works best with 0.005"-0.010", my son's shot out Sako .243 is sub MOA with 0.30+". If he loads a boattail close to the lands, the case neck is holding very little bullet.
- Measure off of the ogive, I'll end up with COAL's that vary 0.005+" just from bullet tip differences.
 
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