Take a look at the article that I wrote about our new resizing die for belted magnums. The article was in Precision Shooting (Feb issue). You can see it, with pictures and all, on my web site at www.larrywillis.com
I've recently talked to hundreds of shooters that know about this problem area "just above" the belt on belted magnums. We are already selling these dies in every state in the US, also in Canada, England and Germany. I'm amazed to see that this reloading problem has gone on for so long without being addressed. We are now collecting an impressive list of endorsements for this new die. The best way to learn about this belted magnum phenomenon, is to try this test. Take a new, unfired case, measure it "just above" the belt, load it and fire it. Then do it again with the same case. You will find that a conventional resizing die can not reduce this area "just above" the belt. Your case grows a little after each firing until it reaches your chamber size (usually after 2 or 3 firings)... then your finished with that case. Our die was designed to resize this area of belted cases, so that you can continue to reload these cases up to 20 times. Too many shooters are setting their dies against the shell holder and are pushing back the shoulder (even while following the instructions in some cases). Their hope is that they will be able to fully resize a belted case with a conventional die. It doesn't work. This causes the shoulder to blow out to fit the chamber and causes case separations. The only solution is to use our resizing die as an "extra step" to properly restore the size of belted cases, no matter if you full length or neck size.
Larry A. Willis