I have a Browning Pump Rifle chambered in 300 Winchester Magnum and I have bought and taken back 3 sets of RCBS full length dies.

The cases all have a pressure ring right in front of the belt and it measures 2 - 3 thousandths bigger than a factory load.

All of them are loaded to the length or slightly less than the length in the reloaders manual and compared to a factory load and within .001 of a inch and still they will not chamber in my rifle.

I also bought two boxes of old Super X Winchester reloads and they will not chamber inside of my rifle either.

I would complain about the rifle, but it shoots sub moa at 100 yards and bulls eyes at 200 yards.

I was told that there is a crimper that you can buy, like the one that you use on the base of a shot gun shell that will resize the base of the .300 shell to make it fit in my chamber. But for now, I use factory loads only in this rifle.

I probably have 10 or more boxes of reloads in my cabinet that will not work, or will work if you force them into the chamber. But I do not want to abuse this rifle and so they can sit for now.

With only 3 boxes of factory loads through this rifle, I hope some day that it will wear a little and the reloads might fit.

So although this manufacturers claim might be a gimic, if it was real, I would also be interested in buying one of their resizer dies.