One more consideration, that I was reluctant to bring up until Daryl touched on it. The depth of rifling may have been substantially more shallow in early days. We know they favored 1:48 twists at times as well. This means that a thinner patch might work as well as our thicker patches in deeper rifling. It might also favor lighter loads than we need. Just a thought.
Not sure about this - every original I've seen the muzzle of, had deep rifling and more times than not, narrow grooves and wide lands - that's the fact part.
My speculation for that is that a narrow rifling cutter would cut those grooves faster than a wide one would cut deep grooves. Why deep grooves? - The deep grooves were probably necessary due to rapid wear/rusting of the soft iron barrels over what we'd call a short period of time. This would extend the useful life before they needed to be 'freshed' out. Deeper grooves would thus hold their accuracy over a longer period of time than would shallow rifling due to taking longer to 'wear' (through rust or actual shooting, which probably never happened) - again, my speculation only. More spec. - deep grooves would allow the use of the thicker materials, animal skins, muslin, or lindsay-woolsey-type cloth with perhaps an undersized ball and still probably shoot as well or better than a smoothbore - certainly at woods ranges and out to 100 yards or more.
The common round ball for the .54 rifles, was the 'trade' or military sized ball of only .520" to .525" in diameter. Perhaps this is why original Hawken rifles were spoken of as being .53 calibre, to shoot the 'trade' ball? Perhaps calling them .53 calibre was a mistake, I don't know - maybe they wer in fact, .54 as many think.
The .54 military rifle had a normally 5 groove rifling - but I don't know their depth, with some European round ball rifles having up to 12 grooves which appeared to be quite deep. The more grooves, the better the 'hold' on the ball. The deeper the grooves, the thicker the cloth (leather) that could be used.
We do know by the mid 1800's, there was a push (Forsythe etc) away from the trend of faster & faster yet deep rifling, to very much slower shallow rifling, which shows us prior to that, the tendency was ion fact, towards deeper, rather than shallower grooves. This was England, however - what happened here at the same time, I don't know. He did note in his book, that the deep 'polygrooved' barrels of the American longrifles, that shot so splendidly at longer range - nearly flat to 100 yards with amazing accuracy to 300yards with what to him, were round balls of otherwise, miserably small size. Unfortunately, I don't think he touched on rifling types, but those, of course, we have the pleasure of being able to view personally.
That 40 or 50 pound chunk gun at Dixon's I saw and hefted, appeared to be close to .60 cal and have rifling that looked like the receptor end for Chevy driveshaft- it had to be .020" deep, maybe deeper & had narrow grooves, wide lands and THIS was a MATCH rifle, pure and simple- kinda opposite to what we might use today. How would it shoot, I don't know, but would have loved to clean her up and find out.
Deep grooves require thick materials and I think perhaps thicker more open weave cloths were in greater abundance 'back then' than thinner tough ones like linen? O'course, Silk will an extra 40 yards - but perhaps only in the mind of a screen writer in Hollywood?
