I fireformed some 303 brass to use in my SMLE 410 conversion.Use 3 gr.of Bullseye pistol powder,jam a wad of newsprint on top of powder,fill case almost to neck with oatmeal and jam more paper into case.Worked good for me with Win. brass although case life is short.I would cut a 410 cartridge open and use the components to load the brass.I had some tools to cut wads to put on top of shot and then a tool to slightly crimp end of case to hold charge in.
If you had .410 ammo why would you be making shells from .303??? You are better off using either .444 Marlin or buying brass .410 shells from Midway/Wideners/Graf...
.410 - .303 is not the same as .410 Shot Shotgun Shells.
...)i seem to remember that a .45-70 will shoot a .410 shell, would it not be more feasable to attempt using a .45-70 in a .410? food for thought........



























