AusVarmint

Out of interest how many people here reload using COAL as it relates to CBTO?

I've just started down this rabbit hole after watching some of Erik Cortina's videos. So I did some measurements using my Hornady OAL kit on different projectiles and was amazed at the variance between CTBO.

I'd be interested in how you are calculating jump etc. based on CBTO and then arriving at a realistic COAL.

PS. Rod, Erik gave you a very positive call out in his video.

Pardon my ignorance cause I'm reasonably new to this game but what's :
COAL means , ie ......overall length mean.
& CBTO means.
Thanks Raven.

barryb wrote: ↑Sun May 05, 2024 7:45 am Pardon my ignorance cause I'm reasonably new to this game but what's :
COAL means , ie ......overall length mean.
& CBTO means.
Thanks Raven.

No problems, I'm learning this stuff myself hence my questions to those here with far more knowledge.

COAL = Cartridge Over All Length. Pretty much what it sounds like "overall length, base to tip".
CBTO = Cartridge Base To Ogive. This is the distance from the base to the ogive. Ogive being where the taper of the bullet first contacts the rifling. From my measurements today it varies from one bullet type to another (in the same calibre).

So, when reloading there are theories as to how to determine bullet seating depth. Either CBTO (with or without bullet jump to the lands) or COAL.

Be interested to hear what the competition guys can share.

Thanks Raven , I had the COAL but I'd always referred to it as OAL & the CBTO , well I had been using that a bit too however unfortunately at the end of the day I still manage a few misses in actual real life.

Yes, OAL is the easier term.

I'm trying to edumacate myself on this reloading stuff. Think I have the basic concept down with CBTO now but I'm sure there's more to it.