I'm not saying this die will solve your problem, but it might. It's on my long list of goodies to buy one day.
http://www.larrywillis.com/
"A Collet for Belted Magnum Cases
Belts on the belted magnum case were put there for headspace control and not for strength, as is sometimes claimed. Once the case has been fired, the life of the case and perhaps accuracy, can be improved by headspacing off the shoulder rather than the belt. This is easily done by backing out the sizing die so that it doesn't set back the shoulder any more than just enough to insure that the case will chamber freely in the gun.
Because of the taper in ordinary resizing dies, the back end of the case (at the pressure ring), is usually left slightly larger in diameter than desired. Innovative Technologies has come up with a clever solution: a collet-type resizing die that sizes the body of the case right up to the belt.
In use, the die body is screwed into the press from the bottom. A fired case is dropped into the top of the die. If it drops in freely to the belt, there's no reason for any further sizing. If it fails to drop in freely, the case is removed from the die body and the collet is slipped over the case until it bottoms on the belt. The case and collet are then pressed up into the die body in the usual way. The collet is squeezed against the case by the die body and resizes it. When the case is removed from the die body the collet comes out with the case and is then slipped off.
Neck sizing, and any required reforming of the shoulder, is then completed using the regular dies for the caliber. All the basic belted magnum cases can be sized using the same collet. This collet die works very well and is a very useful accessory to the reloader of the belted magnum cases.
- Craig Boddington"
"Belted magnum cartridges have been around for over 50 years, and most shooters that reload them are familiar with the case bulge problem that occurs "just above" the belt. This usually happens after just 2 or 3 firings - wasting perfectly good cases. Many shooters have discovered this problem when they find their handloads begin to stick in their chamber, or when they no longer chamber at all.
Unlike non-belted cases, the belt prevents conventional full length dies from traveling far enough down the case. This limits the amount of resizing, and brass is plowed rearward. The brass builds up just above the belt at each reloading, and cases expand. Neck sizing dies don't bump the shoulder back or resize the tapered case wall. The best solution is to full length resize accurately, and use this collet die to reduce case width."
Last edited by PhillipM; 01-23-2014 at 09:17.
Phillip McGregor (OFC)
"I am neither a fire arms nor a ballistics expert, but I was a combat infantry officer in the Great War, and I absolutely know that the bullet from an infantry rifle has to be able to shoot through things." General Douglas MacArthur