So I've been shooting this cartridge and well into my second barrel. What I have noticed is a particular lot of Lapua is quite lacking in concentricity when turning the necks. That alone piss's me off, but I just had a need to start another 50 cases and see that they are about .014" short on the headspace dimension as well this batch.

My thought is to load some very long well engaged bullets and a lighter charge the first firing to form them. But waste of the components just well you guessed it, Piss's me off again!

Maybe a trip thruough the FL die will stretch them out a bit.

Any other suggestions?

I fireform with pistol powder and a wax plug. Have done it for many years.

I would suggest an oversize false shoulder to establish correct headspace, enlarge the neck to a lager caliber, like the .30, and then size down only far enough to get a slight feel on the bolt closure. Use this in conjunction with Butch's method. Don't use the "jam the bullet in the rifling method", it could cause pressure problems.

Thak you both for the learned replies... I shall proceed according to your directions.

Fired some of the new brass today and they filled out perfectly, only used a .284 mandrel, but it created the false shoulder where it was needed.