COAL variances

[Gunpoor]

Hi all! For some reason here lately ive been having to "chase" my overall length around. I trim all my brass to 1.1350 (use a set of Central Tool digital calipers), dies are Hornady Custom Grade with the Microjust seating stem ( I clean the seating die every 100 rounds). I CANNOT get consistant COAL. Just loaded of a test run of 40grn Nosler Ballistic tips shooting for a coal of 1.5850. A few are spot on, others vary by 2 to 3.5 thousandths shorter.... I have found that if i have one where the length is a couple thousandths or more too long, i can run it back into the die and it will drop down. Although the amount varies. Im using a Lee Breech Lock single stage press. Im thinking its the press itself... Anybody got any thoughts???? Driving my ADD nuts!!! Lol..
Thx!!!

[panzermk2]

Not sure, BUT you have to make sure you aren't seating and attempting to crimp on the bullet ogive. If you are on the ogive at all in anyway the bullet will seat correctly and your OAL will vary like that.

[Polockman]

I’ve noticed this too and have come to 2 conclusions:
1. Most of the 40gr and smaller bullets are varmint bullets and have very soft copper jackets. Cases with a little more neck tension resist the bullet seater, causing it to deform the jacket some, rather than pushing the bullet farther into the case.
2. The distance from the point of the bullet to the bullet ogive varies within .003” on any given box of bullets, so you can get a tool to measure that so you can sort them, which should help keep your COAL more consistent.

Personally, I think the neck tension variance is the bigger issue.

[Gunpoor]

Thanks for the responses guys. I dont crimp at this point. But its something that im looking into... Ill have to go through my notes, but iirc its typically on the flat based bullets as opposed to the boat tails... Leads me leaning towards neck tension. Ogive, neck tension, points to ponder...... I will use it as an excuse to upgrade the press thouh! Lol!! Im over-camming the shit out of that little dude resizing these things!!