I never thought about this but I thought it was a good theoretical question (if the particulate was compacted at the charge). I expected the blast would blow through most of the load and send most if not all out, but relatively slowly. So, a fowler would only work with the usual very thick patch (wad) over the powder (I usually use paper) and the also-thick-but-thinner (cardboard) overwad on top of the shot? Never tried it any other way but have been afraid of buck-n-ball "wedging" (like a roller-lock) in the barrel over the ball so do not shoot it but VERY rarely.
As for the underwater thing, I NEVER understood how a gun could be fired there -- the barrel isn't sealed, but I'd think it'd be like firing a very heavy bullet the length of your barrel. I've tried it with a flintlock but can't get a good spark in the lake...
Last edited by HockaLouis; 03-11-2012 at 12:48 AM.