Dan - I have an RCBS Bench Mounted primer tool set up on table beside me as I type - uses "rams" very similar to shown in your picture in Post #7 - I have used so far for Large Rifle Primers and Small Rifle primers - two different ends to hold different diameter primers, but "ram" body looks similar to each. Is a metal lever that presses up on bottom of those rams - I use this thing because it also uses the same shell holders as my RockChucker press, and has long tubes that hold about 100 primers - is similar RCBS device that bolts on to the press itself - but I have never used it yet. I would suspect there must be some relationship between diameter of the "ram" used, and the hole up through that body - to get that "ram" more or less lined up through the hole in the shell holder? Or, maybe the attachment to the press's ram keeps things straight enough to go into the shell holder hole?