[Mr. 16 gauge]

I'm looking for a way to improve my patterns from my trade musket, and one of the things that I thought about doing is to use index cards and curl them so that they can be loaded easily in the barrel, yet will open up when seated on the wadding. the shot (in this case, bismuth) can be poured on top, and the index card will help protect the shot from coming in contact wit the barrel, reducing deformation and (hopefully) improving patterns.
Any see any flaws in my reasoning? Do you think it will work?