In my Harten crimp on the cut down 2 1/2" Remington STS hull I was unable to get the 12 gauge overshot card into the hull due to the irregular shape of the open crimp and had to switch to 20 gauge overshot cards. These are the ones I had tested. I attributed it to an error in the published book. Intuitively, I would think that the Harten crimp using the 20 gauge overshot card would lower the pressure since it looks like it would be easier opening than a standard crimp. Intuition does not always work and Jack may have a point.

So many guns, so little time!