Welcome and not sure - Its just a matter of a relatively thin rim and a whole lot of surface resistance. I lube all my pistol brass with a simple pad. Spray, roll, done. But with .44 magnum I use the same lube as my rifle brass (Imperial wax) and make sure I lube it well. Even then I pulled the rims off three cases today and had to knock them out. They had been reloaded several times. If there is significant resistance when going in the sizing die then its best to stop, remove decapping stem, and knock the case out from the top. Otherwise you will pull off the rim and have to knock it out anyway.