onondaga
posted this
11 August 2015
http://castbulletassoc.org/view_user.php?id=8191>OU812
Man that is a long route. I buy .308 brass to load .308 ammo for my bolt rifles and don't have concentricity or tension problems from Lee Collet Neck Sizing dies and standard Lee bullet seating dies. Both of those specific dies are self centering by design and easily maintain concentricity everywhere under .001” when Lee directions are followed.
If you are jacking your ammo .003” out of concentricity I'd have to really study what you are doing to figure out why. But, I assure you, it is correctable and the remedy will end up being a simple one.
An easy solution would be to modify a .303 Brit Lee collet die mandrel part for placement in a .308 Win Lee collet neck sizing die, or order a custom one from Lee. Custom size mandrels from Lee are inexpensive and ordering instructions for them are at the Lee site. I use a custom collet die mandrel part from Lee for sizing and loading large diameter cast bullets in 7.62X39. It actually was simple and easy to set that up.
Just remember that your fire formed brass has to have a large enough ID neck to be sized down for your bullets or you are looking at a JoeB out of design parameter “dead end failure” with Lee Collet Neck Sizing dies. The collet and mandrel design of these dies is not designed to size up or expand necks, only to size down by collet squeezing a brass neck to a mandrel.
You may not have sufficient chamber neck diameter to load .312” bullets in a .308 Win. You can fight that with neck turning. I don't, and would modify the chamber neck and use a custom die or sell the rifle.
Gary