Yogi- the 48" twist does sound better. I wonder if he measured 1/2 rotation at 24" and reported that as being the twist, rather than doubling it for the true twist.

If indeed a 24" twist, I have very doubtful it will allow 100gr. of powder without stripping. The combination used would have to be very tight indeed, a .495" ball and .025" to .028" patch - more guys cannot load that tight a combination and certainly not without a serious re-crowing of the muzzles.

Most 48" twist shallow rifling .50's I am/was familiar with are happy with, allowed up to about 90/100gr. 2F and gave good accuracy. We were using very tight ball/patch combinations, .495" balls and .022" denim. Shooters today, seem stymied with the combinations we used and claim they can't do it - Oh well.

100gr. of 2F should deliver about 1,800fps to 1,850 which is in the upper range of speeds attainable and about right for most hunting with a .50.

A 75" twist in 12 bore would be perfect for round balls, yet owners of these guns are still looking at slugs for some reason. A round ball, cast soft or of harder lead is much superior to any slug in a ML of that bore size. Slugs show such enormous elevation needed to hit at 100 yards as to make hitting at closer range difficult. Recoil and safety is the stopper when shooting something heavier than round balls.

In calibres this size, it is difficult to get speeds of over 1,400fps - chronographs are the lie detectors here. While pressures are actually very low in the big bores, recoil rears it's ugly head and is hard on stocks & locks too. It takes about 150gr. 2F (5 1/2 drams) just to get 1,350 to 1,375fps in a 12 bore gun. That duplicates W.W.Greener's listed intermediate 'African' load for ctg. 12 bore rifles. The 7 dram (190gr.) load, which gave about 1,500 to 1,550fps with round ball was reserved for very heavy guns of 10 to 12 pounds. Closer to 1890, these loads were apparently increased yet again for the 13 to 15 pound 12 bores to 9 drams(248gr.), still for round ball, I believe, to obtain 1,750fps. This is the speed I achieved in my 9 1/2 pound 14 bore ML rifle with identical loading. That kicks, BTW.

I would not, under any circumstances try that in a Pedersoli 12 bore double. The barrels would probably come off the stock to smack you while driving the tang through your head via an eye socket - either way, you wouldn't like the effect - if you lived, that is.