by Hoot » Wed Mar 20, 2019 4:37 am
The sizing die only goes down so far. I would take a box of factory ammo or buy a box/bag of factory new brass and see if they have trouble. If they do, your chamber could be out of spec. If they don't then it still could be on the tight side of spec and sensitive to even the small amount of case head growth that any case experiences after each shooting. Yes, they all grow, just at different rates depending upon how stiff the were loaded or the platform they were shot in. You can force the sizing die down a little further by reducing the height of your shell holder. I know because I have one modified that way for problematic brass. It is visibly marked so I don't get it confused with one that isn't modified, since many calibers use the same shell holder as the 450b. Do the ones that fail to chamber all the way feel tight when trying to pull them out by hand? That's the sign of case head growth, though it can also occur if your sizing die is out of spec. Though they shouldn't if you clean your brass adequately, dies do wear over the course of their lifetime and they wear wider. If like me, you have more than one shell holder that fits your 450b brass, you can send me one and I'll turn it down a little on my lathe. You can also shorten the sizing die body but that's a lot more expensive than a shell holder. Make sure that when setting up your die height prior to sizing, that you feel a little "cam-over" at the top of the stroke height. That eliminates linkage slop that occurs as your press ages. I keep mine well lubed, to reduce wear as they are an expensive tool.
Hoot
In Theory, there is no difference between theory and practice. In Practice, there is.