I think I found a cylinder but it is $$$ especially for BP.... And well towards the cost of a chromoly steel cowboy action cylinder.
A hammer could be burned out of plate, or convert a typical cheap CVA. But I would prefer to not fabricate to hard.
I was thinking the same thoughts on the loading/ ramrod system.
If you can imagine, I already look like Tuco from the Good, Bad and The Ugly swapping out parts to get that magic combo!