I've been shooting C&B revolvers, including a pair of 5-1/2" SS ROAs, for ten years now up thru 2009 in CAS matches around the USA. That equates to thousands of C&B shots fired.
I have never, ever, used any kind of reloading base/block structure, whatever, when reloading my revolvers/cylinders. When reloading my C&B revolvers, I load the blackpowder into each chamber, then I push a Wonder Wad into each chamber, and then place a lead ball onto the top of each chamber and operate the ball rammer chambering the ball while holding the grip frame against my tummy.
For me that is the easiest way to reload a Cap & Ball revolver.
Coop