I have been pressure testing IMR7977 with 180 grain Berger Hybrids in a 7RM and after 3 firings the Norma cases started to chamber hard, even after sizing in full length Redding bushing dies. Headspace was checked and verified not to be the problem. I had previously purchased the Innovative Technologies: "Belted Magnum Collet Resizing Die" and decided it was time to give it a try. This die is designed to resize a belted magnum case right above the belt where the case expands due to excessive pressure. Fired cases measured 0.5145 right above the belt. New Norma 7RM cases measure 0.510 right above the belt. The Collet Resizing Die is interesting as the die goes in from the underside of the top of the press, not from the top as regular sizing dies do. The collet is removable and needs to be placed on the case, positioned all the way down to the belt before the case and collet are driven into the sizing die with the press. Cases and the collet need to be lubricated well, Imperial Sizing Wax worked very well for me. The case and collet exhibited significant resistance when inserted into the die for the the first few cases. The case and collet would only go part way into the die without feeling like they were going to stick in the die. The case and collet were removed from the sizing die and additional lube was added. This was repeated several times until the first case went fully into the die. After about three cases the case and collet would go into the die the first time. It seemed like the collet had to wear into the inside of the resizing die. Cases 4 through 10 resized well on the first try with only nominal pressure required to actuate the press. Afterwards all 10 cases measured 0.510 immediately above the belt and chambered with ease in the 7RM. Thoughts? dwm As an aside, the Norma cases still hold primers, although it does not take a lot of pressure to install them in the cases. I plan to reduce the load and work with seating depth next.