brilliant thanks.Made, usually, to de-cap Berdan primed 9mm Parabellum aka 9mm Luger brass.
Uses just a drop of water so much more efficient than the Wamadet Heydraulic Decapper. There will be a spigot or "end" on your prime that is a snug tight fit into a 9mm case. You place the thing on the base (that has a hole in the centre) and hit the top of the Prime with a hammer. The drop of water drives the primer out of the case.
The biggest drawback is that, nowadays, time is money (it takes a lot of time), the cases get wet so need to be dried, Berdan primers are now virtually unobtainable, eventually you'll mix up a Berdan case with a Boxer case and wreck the de-capping pin and rid in your die set, seating Berdan primers in a progressive press is an explosion risk.
The same company that produced the Hydro-punch also produced a die for converting 9mm berdan primed cases to boxer primed. Unfortunately it wasn't an entirely reliable system due to a number of variables and the new boxer primers would be a very loose fit in some cases and often blew out on firing.Daft question time. Is it worth drilling out the primer pockets so you can fit a boxer primer? Or are the pocket dimensions different?