Loading fourten for a repeating gun can be tricky. You do need a means of sizing the cartridge head. Single shots tend to cope with unsized cartridges if reused in the original gun.
The other issue is due to high pressure and temperature the plastic swells. Even on a single shot it gets difficult to chamber a hull that's been reloaded a few times, forget it for a slide action so budget on replacing the hulls after a couple of reloads.