Bobby Hoyt made a .45 barrel for me and recommended a 1:56 twist. The accuracy sweet spot is around 55-60 grains.
opinions of best twist rate for 45
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longcruise
70 Cal.
You are probably good with just about any of the typical rates for a 45.
Maybe there is something to be learned there.
The ultimate slow twist is a no twist smooth bore. I don't shoot them but many of our members seem to get pretty good accuracy with them. The "conventional wisdom" applied to round balls is the larger the ball the slower the twist. And the reverse, the smaller the ball the faster the twist.
If Kibler's SMR shoots as well as reported, and I believe the reports, maybe the degree of twist for our RB guns is less relevant than we think
????pchwcf50110
40 Cal.
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1-48'' in a .45 caliber is a great round ball twist. Generally speaking as you go up in caliber with a RB the twist can be slowed down incrementally. I have a .69 caliber October Country Great American Sporting Rifle with 1-104" twist but it really doesn't need to be that slow. A .50 caliber in 1-60" and slowing to a 1-80" when you get to .72 caliber will work great.
I have Rice 45s with 1-66 which I thought would be a little slow for milder target loads. But with 50gr at 100 yards from a bench rest will make you grin from ear to ear. They are square cut style American Heritage series.
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olskool, I'd reckon the 72" twist would be a honker with a long enough barrel.
Saying that because it and the shooter might be happiest with much velocity.
I started out with 48" twist .45. One of those percussion Kentucky" rifles of the early 70's with a piece of brass wrapped around to hide where the two pieces of the stock came together. With 65 grains of FFFg it cracked like a bullwhip and was accurate as far down range as until the ball slowed down. That may have been when it transitioned to subsonic but I can't swear to it. But I pulled off some fine shots a long ways off with it. My thoughts are along the lines of that gosh, if the 72" twist required you to get the velocity way up in order to have sufficient RPM's on the ball then having sufficient barrel length to help achieve the velocity and to also give you a long sight radius to help with long range accuracy, long enough to make use of that high velocity before the ball slowed down and started going coo-coo, well, it might be a winning combination for extended range flat shooting. As far as you could do with .440 or .455 round ball anyhow. I'd have to break out the books to check on velocity drop but it sure does slow down quickly.
Saying that because it and the shooter might be happiest with much velocity.
I started out with 48" twist .45. One of those percussion Kentucky" rifles of the early 70's with a piece of brass wrapped around to hide where the two pieces of the stock came together. With 65 grains of FFFg it cracked like a bullwhip and was accurate as far down range as until the ball slowed down. That may have been when it transitioned to subsonic but I can't swear to it. But I pulled off some fine shots a long ways off with it. My thoughts are along the lines of that gosh, if the 72" twist required you to get the velocity way up in order to have sufficient RPM's on the ball then having sufficient barrel length to help achieve the velocity and to also give you a long sight radius to help with long range accuracy, long enough to make use of that high velocity before the ball slowed down and started going coo-coo, well, it might be a winning combination for extended range flat shooting. As far as you could do with .440 or .455 round ball anyhow. I'd have to break out the books to check on velocity drop but it sure does slow down quickly.
Not only the twist rate is involved for PRB, remember you need the grooves in the .010 - .016 area. I like a 1:56 for PRB & .010 - .012 groove depth. I seldom shoot one past 75 yards hunting.
Several years ago I sent a barrel to Bobby Hoyt to have enlarged to .45 from .36. I let him "do his thing" since he's the expert. 1-56 was the twist he used and IIRC a .012 groove depth. Grooves wider than lands. That barrel was a tack driver!
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