So to clarify, the bismuth shot is non-toxic and can be loaded straight in the barrel like lead shot (without a cup) and will not harm the barrel? If that is the case than it sounds like the logical choice.
Yes, it came out after all the problems with steel shot, it's non-toxic, and it's weight it's performance is figured the same as lead shot performance...cups not required for bore protection like with steel...treat Bismuth like you would lead.
Should I use the cups anyway? (.54cal smoothie)
This is an area that you probably need to decide for yourself based upon what you're trying to accomplish.
For example, I just recently got a .54cal smoothbore myself and sighted it in last weekend...but I intentionally did so without the use of a modern plastic shot cups, because they old timers did not have them available back then, and I wanted to try to duplicate most of how they did it back then.
So in my .54cal Flint smothbore, I settled on 70grns of Goex 3F, 1/4" lubed wool wads (two 1/8" wonderwads), 1+1/8oz #6's, and a Circle Fly overshot card...beautiful even 25" pattern at 25yds, several pellets will hit a coke can at that same distance, etc.
In my .62 Flint smoothbore for turkey loads, I also do not use modern plastic shot cups...I do use home made paper shot cups because they could have done that back then if they wanted to.
So it's really a decision based upon what you want to accomplish...if you want the satisfaction of being able to say you've taken game with it "like they did back then", can you really say that if you use modern plastic shot cups, etc...
:m2c: