Twist rate for .45 pistol

[Cornbelt]

I have a bbl. w/1 in 22" twist. Would this make a good pistol?

[Flint]

44 mag and 44-40 twist is 1:20  45 Colt is 1:16   45-70 is about 1:20.  22 is kind of slow for a conical, but would be OK with a light bullet or a roundball.

[bedbugbilly]

This is more of an additional inquiry than a reply - but - could someone who is knowledgable on the subject of "twist" give some more in depth explaination of the "twist" rate and the effect on the accuracy, etc.  I don't know if the original inquiry was concerning a barrel for a single shot muzzle loading pistol or for use on a black powder cartridge pistol.  In regards to barrels used for single shot muzleloading pistols, Green Mountain Barrels are listed in Track of the Wolf as follows:

.32, .36 & .40 caliber - 1 in 16" twist
.45, .50 & .54 caliber - 1 in 20" twist

Why is the twist different on the smaller caliber barrels from the larger caliber barrels?

I a person used a rifle barrel, with say a 1 in 48" twist and cut shorter barrels out of it to use to build pistols (I'm talking single shot black powder pistols), esentially the pistol barrels made from the rifle barrel would have a much slower twist than say 1 in 16" or 1 in 20".  What effect would the much slower twist have in comparision to a barrel with a faster twist?  I'm assuming that it would affect the speed of spin on the patched round ball - would this affect point of impact or what?

These might be dumb questions but if someone could explain the rate of twist and the effect on patched round balls, it would be a big help to some of us who are better "builders" than engineers.  Many thanks - any information would be appreciated.  Sorry for adding this as a reply but it pertains to the question asked and could be of help.  Thanks!

[Flint]

The longer the bullet is, the faster it must spin to gyro stabilize it.  That is why you have to spin a football when you throw it.  The smaller 30's caliber conical bullets are generally longer in proportion than the 40+ calibers are, look at the difference in profile between a 45 Colt bullet and a 38 Special bullet.

Good question on the pistol barrel twist, as they tend to be faster rates, and perhaps velocity is the difference, a faster (rifle) bullet needs less spin?  Typical Dixie Gun Works single shot pistols have 1:18 twist, but report the Italian 44 revolvers with rates like 1:60 (Walker) 1:32 (Army), or in a 36 caliber Navy 1:18.  Uberti specs 44s at 1:18, but the Patterson at 1:56.

This is all over the map, so who knows what works best?

A roundball needs much less spin than a conical, and muzzleloading rifles generally have a fairly slow rate of twist, typical are 1:56 or 1:64, but as fast as 1:48.  The TC rifles were made to use the longer, heavier thompson "Maxi-ball" bullet, and had the faster twist, 1:48, and were reportedly not as accurate with a roundball as more traditional bores, but I didn't see mine as less accurate.

[coyotejoe]

Rate of twist is only half of the equation, velocity is the other half. A rifle with a 48" twist and firing its ball at 2,100 fps will spin the ball at 31,500 rpms. A pistol with an 18" twist but only 800 fps will spin at 32,000 rpms, or roughly the same rate of spin. Lower velocity is why pistols need a faster twist. As to why a smaller caliber needs a faster twist, think of it in terms of "surface speed", you would turn a 1/8" drill bit much faster than a one inch bit.  A 22" twist should be fine for a .44 caliber or larger firing round balls, for a .36 caliber I'd want a 16 or 18" twist but I wouldn't discard the 22" either. Most cap & ball revolvers have twist rates of 32-36" and they shoot balls just fine. Original Colts C&B revolvers used gain twist rifling and I don't even want to get into that.

[bedbugbilly]

Thanks Flint and coyotejoe!  That helps a lot.  I remember "gain twist" barrels from years ago - if I remember correctly, there were several manufacturers of them - most fellas I knew that were building rifles still preferred to stick with the traditional type of rifling.  Your comparison to drill bit size and speed makes a great correlation.  I greatly appreciate the information you fellas provided!  Many thanks!