overall case length question

[Rocky Raab]

denton, that's because the nose shape varies between your two examples.

That's why I don't use COL (cartridge overall length) at all except for magazine length restrictions.

The important dimension is from the case head to the datum line on the bullet where the ogive reaches bore diameter. That's the circumferential line on the bullet that will touch the lands.

I call it the bore line, and once you find the place that gives good accuracy, if you measure the case head to bore line and record that number, you can repeat the same Headto BoreLine (HBL) length with any bullet. Simply scribe a ring on the bullet at bore diameter and adjust the seater until you match your recorded HBL.

BTW, that ring on the bullet is at bore diameter NOT groove diameter. In a 30-cal rifle, it'd be where the bullet is .300", not .308"