I've still got some FF that I used on my rifle.
I bought a flask that came with a 24 spout and I ordered a 20 also. If I keep the powder charge light, I should be OK.
Just made a post on getting a new 1858. I won't have to worry about the powder charge on it!....but what about the nipples? I'm hoping that just getting some #10 Remington nipples will be ok with it.