Neck up or neck down?

[cccombo]

I want to use Lapua cases for my 7mm08

From what I understand if I neck up .243 brass it could create 'doughnuts' which could cause excessive pressure
and if I use .308 brass I might need to neck turn and the .308 case has a shorter neck than the 7mm08/.243 and that can cause inaccuracy?

Will be using the 7m08 on small things when it's to windy for the .222 so want varmint accuracy


What will be the most trouble free option?

 

[jr600yd]

I would neck up. It takes the least amount of case prep and you won't get the 'donut'. The dreaded donut appears when you neck down. Should you choose to use 308 brass FL size them first in a 308 die then neck turn them. Neck turn all the way to the shoulder then keep going. If you cut into the case shoulder for another few thous. it will greatly reduce the amount of 'donut' you will get.

 

[Preacher]

You will need to run a expander into the necks before they can be turned, full length size one and your not going to get the cutter to go into the case neck....
Short necks don't necessarily mean inaccuracy...

 

[Ackman]

Chambers are either longer or a lot longer than the brass. Use one of those gauge plugs from Sinclair to find out your chamber length. It'll probably be at least .020',could even be .030') longer than spec dimension for a 7-08 case. A .308 case is already about .020' shorter than the 7-08. And all the Lapua brass I've measured was right at trim-to length which is another .010' shorter. So you'd wind up with brass considerably shorter than the chamber. Like adding another .050' or so freebore only worse because there's an edge there. If you're set on Lapua, I'd use .243 brass. Necking up is real easy and don't worry about creating a doughnut. But if it were my gun I'd just use Win. brass and be done with it.