Bullet Comparators

[rikman]

Anybody use a bullet comparator for precision loading of rifle ammo?
I'm currently loading 10 308Win rounds. I'm using 168gr Hornady Amax's and Lapua brass.

Also have some new tools. A mitutoyo micrometer accurate to .0001" and a Redding Instant Indicator setup to measure seating depth right now,(from the ogive if I'm not mistaken)?

I've loaded about 4-5 rounds and saw that I had to adjust the micrometer on the competition seating die every time, mind you it's only .003-.005". I checked them on the Reddding II and saw variances of about .003"

So what is the preferred technique? Setup the die to set X inches as measured from the ogive and not concentrate on col as long as round fits in a magazine if gun has a mag for feeding?

 

[RAT807]

I loaded up 20 rounds for load testing a couple days ago and my OAL was within .0015. I called it good thinking it's probably from the bullets. I have a second comparator on order so I can measure the bearing surface of the bullets to check for length differences.
Out of 20 bullets loaded, 120gr Hornady HP, I had 13 at 119.8grs, the rest were either 119.7 or 119.6. The whole box ranged from 119.5 - 120.6 so this alone could cause the different OAL. I also rotated the cartridge or rocked it back and forth to be sure I was measuring from the center of the case (cartridge straight in the caliper/comparator).
Oh, one more thing. Try to notice the speed you use on the press arm. It seemed like if I went too fast, the bullet would seat a tad deeper. I'll verify that on my next session.
I would set it up measuring to the ogive once the magazine measurement and jump to the lands distance is known.