I have both the old and new RCBS hand priming tools - one requires the shellholder, and the other is universal. As mentioned above, the older model has a free-floating ram that falls out if the tool is upside-down, the new model's being threaded in. I like the feel of the older tool, as the jaws flex in the newer tool giving it a mushy feel. Still, both tools work great, and I will continue to use them - one for small, the other for large primers so I don't have to reconfigure the tools. The universal does have a bit of a weak grip on my .223 cases, and sometimes they fly out of the jaws and across the room. I therefore reserve my universal primer for my large-primed cases, as they tend to have a larger diameter.