Ralph Walker, in his gunsmithing book, tells of a S. American gun that was sent to him for evaluation. He said it kicked like a mule, so he called them about it. Come to find out, the S. American manufactured cartridges, have a thick rim. When he received a supply of them, he said recoil was drastically reduced. I have noticed that the rims on Federal paper looks to be much thicker than the customary plastic shells.

Lenard