I've not torn it apart yet, but every video Ive seen of reassembling rossi r92s mentions using a "dummy round" to make it easier. The carbine I have is a 38/357 mag. I know they are slightly different in length. Would I be able to use 38 spl snap caps for the dummy round, or must it be 357 magnum length? Not new to the cartridge,just the firearm.