Best twist rate for a Smith Carbine reline job??????

[Smokepole50]

I would like your opinions on the proper twist rate for the Smith Carbine. I'm getting a new liner put in my Smith and what I am discovering is that what most people are using does not match with what should be. Based on the Greenhill formula and my experience with fast twist muzzleloader's such as the 1:28 Green Mountain Long Range Hunter barrel I bought years ago for my 50 Cal Hawken I am thinking a 1:36 twist would be correct.

As well, while I have your attention, what are your thoughts on number of grooves. I'm thinking at least 5, maybe 6.

Thanks for your thoughts and experience.

Randall

[Lou Lou Lou]

I have been very happy with my three land and groove Hoyt reline. He picked the twist

[gemmer]

I have been very happy with my three land and groove Hoyt reline. He picked the twist

He just did an Erma Gallagher .50 cal for me. He used 1/56.

[jonk]

Depends what bullet you wanna use. A decent rule of thumb is, the faster the twist, the heavier the bullet it will stabilize.

Most smith shooters use something in the 340 to 400 grain range. That's a fairly narrow range, and I'd l let the barrel liner maker dictate what twist to use, or offer suggestions. If you wanna use something lighter or heavier, then specify that when you get it done.

[Smokepole50]

Thanks for the comments guys. I am a WHY kind of guy and I can't help but wonder why 1:54 works with a bullet that is 1.5 times in length over it's caliber. (360 gr Hoch mold) It must be enough to stabilize the average Smith bullet at 50 to 100 yards but I wonder how narrow that makes your powder charge window and if you could hit a basketball at 150 yards.

[Smokepole50]

Why does Henry use a 1:20 twist for there 45-70 lever action rifle? Their 300 gr bullet should be about the same length as most Smith bullets so why don't they use 1:54 or perhaps 1:48. Barrel length is not an issue with their 18.43" barrel and velocity should be higher with a 45-70 so why are they spinning there bullet faster???Berger has a bullet stability web page.......With a BC of 200, 360 grain bullet, .515 Cal, .766 length and 750 to 950 fps there calculation calls out 1:36 to 1:40 twist rate.

[gemmer]

Why does Henry use a 1:20 twist for there 45-70 lever action rifle? Their 300 gr bullet should be about the same length as most Smith bullets so why don't they use 1:54 or perhaps 1:48. Barrel length is not an issue with their 18.43" barrel and velocity should be higher with a 45-70 so why are they spinning there bullet faster???Berger has a bullet stability web page.......With a BC of 200, 360 grain bullet, .515 Cal, .766 length and 750 to 950 fps there calculation calls out 1:36 to 1:40 twist rate.

Maybe I'm missing something, but why would they want to rifle their barrels with a twist that limits them to short, light weight bullets?

[Kevin Tinny]

Hello:

Faster twist for longer bullets. A 45 caliber, three caliber long, 500 grain cast bullet at 1250fps muzzle velocity usually requires a twist between 18" and 20 inches.

I shot a 59 caliber, 3.5 caliber long bullet weighing 1250 grains at 1250 MV in an 18" twist for over 15 years. It performed very well out to 300 yards. Ok, it weighed 56 pounds. My line mates often used 45 caliber in 20" twist -- very effectively.

Velocity changes are relatively uninfluential on stability compared to bullet length, especially at black powder velocities.

Beware: The Greenhill formula only points to minimum twist and was more for artillery. I found it useless.

Regards,
Kevin Tinny