Interesting - I wondered if it had something to do with putting a definite spin on the ball. Now we know. You should be able to do that with a pure lead ball - all you'd need to do is to take a chance. It probably wouldn't shoot any worse - that's for sure.
My feelings on spin, is that if too much spin, would make the ball react like a climer baseball. It might remove the windage error though and that would be a bonus. The higher the velcity of the ball, perhaps the more spin would result. A paint ball is running 280fps - our musket balls are running 800fps to about 1,200 or 1,300fps. I have to wonder if the 'kicker' would either be too effective, or not effective enough with the higher speeds we're using.
I've watched slow moving round balls that take on a spin in the air (through binoculars) - divert exponentially with increased range. Normally, to increase the accurate range of a smoothbore - you have to drive the ball faster so it goes farther before it takes on a spin.
My double 12 bore, 1900 era ctg. gun would hold into 10" offhand, alternating rights and lefts, at 100 yards - but it took 190gr. 2f to do it - yeah it kicked. Then I found smokeless at the same speed, gave me the same regulation, with 1/3 the recoil. I was using my .684" ball of WW or pure with the sprue filed off and specialty wads to hold the ball centred. Pertenant to this thread, is that at 1,550fps that ball was quite accurate right to 125 yards and like a patched ball, was delivered with out any spin at all. Too, I was using a rib mounted scope for this testing. the faster i drove the balls, the longer accuracy range I had. Off the bags, it would hold onto around 5 1/2 to 6" with BP or select smokeless loads.
Balls without sprues should be more accurate art range, than balls with a sprue as there is less 'surface' irregularity to cause a spin to start. Of course, internal defects, like air pockets will also cause a spin to start - or grossly irregular flight that increases exponentially. It is demoralizing to see a load that shoots 1" at 25 yards for 5 shots, open up at 50 yards off a rest to where 5 shots doesn't produce 5 holes in an 8"x11" sheet of paper. The lack of a sprue is one reason I prefer Jeff Tanner moulds for large calibre smoothbores.
Heavier charges for increassed range is one reason why the US paper ctg. loads held so much powder- they wanted to achieve 1,700fps & thought they actually did, with the 165gr. serpentine powder, then 130gr. with the more powerful amalgamated powders of post 1820 or so. Their main problem with accuracy, was the grossly undersized balls they used - .64 cal to 1820 or so, then .65 cal balls. The issue muskets ran .69 to .70 cal. and the paper, while taking up some of the windage, didn't take it all up.
BrownBear - if you don't want to 'ding' your muzzle to make a 'kicker', send your barrel to me and I'll do it - to it - in the intersts of science, of course.
