Halfadouble,
In my considered opinion, 1/16 of a sheet is not nearly enough for a 45-70 size case. I wouldn't use less than a 1/4 sheet, even in fireforming loads where it is held in place by being filled with grits/cornmeal/worn polishing media. It is likely that 1/16 sheet wouldn't stay in place long enough to get to the truck, before going to the range.
Mike