I make 8 bore ammo from Remington Industrial cases. You will need to re-size the step in the head and a roll crimper to finish off. Chamber lengths for 8 bores were 3 1/4", 3 1/2" 3 3/4" 4" and 4 1/2" there was also a chamberless 8 for thin brass cases. The Industrials are 3 1/4" which can be used in any chamber. 10 to 1 your gun will only be proofed for black powder. Have the barrels checked to make sure that they are still o.k. Don't worry about using black as this gives excellent patterns. Card and felt wads also. Plastic can be obtained but are not suitable for black unless you don't mind wire brushing melted plastic stuck to the inside of the bore. Black burns hotter than nitro. Lagopus.....