http://stevespages.com/jpg/cd65x50arisaka.jpg
"Need them most of the time", if the case head diameter of the 6.5mm50 Ariaska is .447" the person doing the forming is going to need something I have never seen. I have found other advantages to forming 308W from 30/06 cases; there are times the chamber neck is generous. I hear a lot of talk about machine gun chambers and cases fired in machineguns, and then there have been many bolt rifles built with machine gun barrels. POINT? I was asked to make a shop call, seems a builder of bench rest type rifles with very heavy barrels had a problem with a rifle he build and sold to an Internet savvy reloader. He was complaining about 'loose necks'; I ask about accuracy, there was no way to improve on accuracy so I boxed up a bunch of dies and went for a visit. We settled on LC NATIONAL MATCH 30/06 cases, I formed 300 cases. By using part of the case body to form the case necks the clearance between the neck of the case neck and chamber neck was .002".
Problem, the owner of the rifle does not want to share his cases and or leave them laying around on the ground at the firing range because the thick necked 308W cases will not allow the bullet to be released willingly. And then there is annealing.
F. Guffey