I was surprised about the drums, but CVA did a good thing with them, being screwed through the side of the barrel into the breech plug.
Otherwise, as normally done, just into the barrel, it would likely have blown from the BP overload, let alone the 80gr. stricken measure of H110.
I just filled an 80gr.(Scheutzen) 2F measure, with H110 and got 80.4gr.