: I do not bleieve for a second that balls develop more pressure than a shot load, with it's attendent length of shot column, extra wads, etc increasing pressure through friction in the bore. I may be wrong, but that is what I believe. We've developed ball laods for double 12's, no problem, even those with damascus barrels. They must be in excellent shape though without ANY deep pits or dings.
: Since we are talking about more modern guns than muzzleloaders, we are referring to ctg. guns that used, for expample in 12 bore, shot charges to at least 1-1/4 ounces. That is a .715" ball, weighting 545gr. compared to the shot charge of 546.6gr. Looks pretty close to me. I'd use that ball in a set of damascus barrels IF they were in excellent condiditon as checked out by myself. 'Fluid Steel' barrels in reasonably good condition would also pass.
: The barrel thickness at the muzzles for shooting round balls and black powder is not a major concern, as long as they are 'sound' and not wafer thin. W.W. Greener made up a double gun, with very thin muzzles. He fired many pigeon loads, heavy by the standard of the day, without damage, then cut a full circle off each with his pocket knife, just to show the low pressure at the muzzles. This was with BP, as smokeless developes higher muzzle pressure than with the black powder. Too, even with smokeless powders used in shotshells today, muzzle pressure is still quite load, not at all like a small-bore rifle.
: I've come across some more information on English trials with bore guns (small bores too) and will pass that along as I gather it into something readable.
: Regulation is something one must experiment with. As with a double rifle, you simply cannot pick a load from a book and expect it to regualte.
: The ultimate would be to have, as happened with my old 12 bore shotgun, a load that will put the barrels side by side out to 100 yards and with suitable accuracy to that range. In their day, with supplied ammo, there were lots of doubles that didn't regulate well, however the 'best' names usually did.
: The second best situation is to have a double that shoots exceptionaly well with one barrel, to the sights, saving that one for ball and the other for either shot or at least knowing where the other shoots and using it only for a 'back-up' or stopping shot if necessary.
: Samual Baker was most impresed with the .577, loaded with 6 drams of powder and a 650 gr. bullet. With it, he said it never failed to paralize a lion or tiger (India). Another African hunter claimed his .577 was a tremendous gun for Elephant, he-too using a black powder express double rifle.
: The 'Field" tests in England, using small bores, the large bore rifles and smooth bored ball guns was quite interesting. I suggest anyone interested in this aspect of shooting, big guns and small, find a copy of W.W.Greener's 9th edition as noted above in a previous post. A better record of these gun's history is not likely to be found. As well, there is a wealth of knowledge to be found within, regarding shooting shot well. Without this book, it is unlikely I'd have pursued finding round ball loads for my own 12 bores.
: The shooting of Holland's 8 bore and 4 bore was especially well done, as was the 12bore, all managing less than 1" deviation from centre at 50 yards. All were shot with round balls, including a 1,880gr. conical from one 4 bore.