Dave, the issue isn't getting the round ball up to bore diameter, it's slamming a .678 round ball through a .640-.642 choke, unless I've misunderstood what you mean.
Tom, that is the question my mind keeps coming back to, is that too much constriction. My 20 bore fowler, cylinder bore, will lay patched .600 RB's into a 2-3 inch group at 40 yards with boring consistency. Even if it wouldn't mess up a fine old firearm, with that much constriciton am I going to be able to hit anything with it.
Then I think, "get a smaller RB mold" but with pure lead RB's obturating to bore dia. we're back to the same situation. The bore mics .680 for at least the first 2-3 inches in front of the chamber so I'm back to what I started with....sheesh!!!!
When I was cleaning the barrel yesterday I learned that the choke does run back down the bore from the muzzle for 3-4 inches. and it's pretty tight. A 20 bore jag with a doubled T-shirt patch wouldn't go through it without a lot of push.
Mike, I think you're right.....too much sugar for a dime.
