[Brian Pfleuger]

Also try removing the bolt, pushing the case firmly into the chamber by hand and gently pushing it out with a cleaning rod from the muzzle. That ensures that the bullet isn't sticking in the rifling. If you get the same measurement both ways, you can be confident that it's correct.

The next question is if rounds that long will fit in your magazine, or if you care that they do/don't.

Nothing wrong with 0.020 but nothing special about it either. If that number is what you want to use, start at minimum starting loads and work up in 0.7-1.0% increments.