Has anyone ever successfully de-capped a Bredan primed case? I've tried it using a wooden dowel and by driving an unfired bullet into a shell casing full of water. I've ruined cases and shot water all over the place but have never managed to remove a primer. I Have tried this with 8mm Mauser, 7.35 Carcano and 7.62x39. No joy.
I have a method I plan to use but have not tried it yet. It requires drilling a centered primer hole in the case base. My plan is to use a decapping rod with a drill bit inserted into the decapping pin holder and using it as a mandrel. The process will require not drilling through the used primer. Once the drill press is set up and the case is inserted into position it should be an easy job.
I have come across two methods that people say works. One is by Marshall, at a forum. He uses a file ground down to a small enough tip to tap out the primer in on of the berdan flash holes, then the other, back and forth, until the primer comes free, relatively undamaged. He says it works most of the time, and with practice take about 10 seconds.
The other is a device to hydrologically remove the primer by placing the case in the bottom of a pipe. There is an O ring around a hole in the bottom, which is large enough to allow the primer to pop out. The base of the cartridge seals the hole and the pipe filed with water. A large piston is put in place above the cartridge, the piston is hit with a sledge hammer, the primer dislodged without damage to the case or primer cup.
There is a Youtube video demonstration.