bonanza - I don't for a minute think a bullet has to be in a barrel for 1 turn, or even for 3/4 turn or carbines and handguns wouldn't shoot well at all. Even my 50/70 Sharps shoots well with it's 42" twist and 22" barrel, with my modified mould. I am certain that if the barrel was 2" shorter, it would shoot just as well, even thouth the bullet turned less than 1/2 turn inside the barrel.
; Dan may be onto something with the rifling being handled with available equipment, except the .50/70 Sharps had 2 main twists, 42" and 24", but then, depending on which armoury made them, so Dan's theory may hold weight.
: I was merely unlucky in getting a re-lined 1859 barrel with a 42" twist, but agin, it does shoot well with bullets that require only a 38" twist according to the rifling formula. That barrel has the longer, 1.9" chamber, not 1 3/4" normally associated with .50/70's. I expect tollerances with the first centrefires weren't very narrow.
: With McGowen 24" twist .50 cal. barrels, Taylor and I managed 10" to 12" groups at 450 meters with our Rolling Block and Sharps rifles, both with Mcgowen barrels and chambered for the .50 Alaskan. We used straight BP loads with OxYoke wads and 550gr.RCBS and 525gr.Lyman bullets. We were shooting off the hood of my truck. Our sights consisted of Globed pin-head front and tang mounted aperature sights. Rifle weight was identical at 11 1/2 pounds. My RB routinely ran 5 shot, 1 1/2" groups at both 100 and 200 meters using 550gr. RCBS bullets. Taylor's rifle, iwth 520gr. Lyman cast bullets wasn't as accurate close up, but at 450yards, it matched my Rolling Block for accuracy.