Not only feasible, something like that has been done already. Check out what the 13mm Gyro Jet cartridges did. They had holes in the back around the primer, so the primer stayed in place. FYI, the hammer on the gun actually hit the front of the cartridge, driving it back into the firing pin which started the ignition process with the primer. The cartridge then fired off and pushed the hammer back down, re-cocking it as it went by on the way out.