As noted above , the Lyman 310 tool is a plier like tool that mounts a die on one side. It is still available. Lyman Products
I believe that the dies are a proprietary size.
I remember seeing a cowboy shooter at a match decapping his .45 Colt black powder brass between stages with apparently little effort. He was using a 45/70 decapper die which allowed him to rapidly decap so that he could get his brass into a jar of cleaning solution.The 45/70 is a slightly larger diameter so there was no sizing.