Appropriate Twist by Caliber

[Eric Smith]

I read somewhere here that a .45 caliber rifle shoots most accurate with a 1-56 twist. Is that true and are there other "best twist" for other caliber barrels? Does Barrel length figure in?

[Habu]

"Best" for what?  "Most accurate" at what range, with what load, for what purpose? 

I don't think you'll get much support for the idea of a "best twist."  Twist is just one of many factors to be considered. 

[Hungry Horse]

 I suspect 1-56 in a .45 cal. rifle will shoot better over a longer distance, because you can load it a little hotter than a standard 1-48 twist, and still not lose accuracy due to the ball skipping over the riflings. I have a gun with a Douglas .45 cal. barrel in 1-66 twist. It shoots good, but won't outshoot my friends 1-56 twist on a regular basis.

                        Hungry Horse

[zimmerstutzen]

I have an H&H target barrel in 45 caliber with as I recall, a 1:66 or 1:72 twist.  It is far more accurate than I am.

Accuracy is certainly relative and I don't know that there necessarily is an optimum twist just based upon caliber.    Intended powder charges and uses have a lot to do with it. 

A person who shoots mostly offhand to 50 yards can do quite well with a fast pistol twist in a rifle and conserves powder by being able to use light charges.    Whereas a 100 yd shooter probably needs a little more speed to lessen the effects of crosswinds.. 

Now, I have seen that as a general rule, twists offered by barrel companies seem to get  faster as the caliber size drops.  ie 32 cal has a faster twist than a 40 cal and that a 45 cal rifle barrel twist is slower.  After that they all seem rather slow.

[BrownBear]

I've never seen a formula that defined "best" to my satisfaction before launching into the #'s.  I've evolved my own rules of thumb that work for me, but aren't intended for anyone else.  In general really fast twists intended for modern projectiles can be made to shoot quite well with RBs, but as velocity goes up I need tighter and tighter patches to make them perform.  At top powder charges it's contra-indicated because the patch has to be so tight it takes a serious mallet to do the starting.  

On the other end of the twist scale, I've found there's such a thing as "too slow," for my shoulder at least.  Large cals with very slow twists require huge powder charges (for my taste again) to achieve optimum accuracy and perform poorly with light to moderate for-caliber charges.  I have a 110" twist (or is it 112"?) 62 cal that doesn't really start settling down to fine accuracy until I move past 140 grains of powder.  No plinking with that one.  I have another 62 cal that's either 62" or 72" (memory suques with old age) and it performs brilliantly from 60 grains up through 120, as fast as I've pushed it.  I have slow twist 58's and others as fast as 48" and they're much the same about light versus heavy loads.  

But a formula? Depends on what you're doing with the gun.

[Vomitus]

   The anticipation of 0 twist in 50 inches is beyond belief.Soon you'll see why. Rifling is way overrated,lol!

[billd]

For round balls Bob Hoyt told me the caliber times 1.25 is what he uses unless the customer specifies differently.

Bill

[Daryl]

For many years, match rifles, those used by serious shooters in the buffalo and bench matches at Friendship, were 48" twist - at least to .50 cal.

My 60" .45 cal GM barrel has shot many .4" to .7" groups at 50yards off the bags.  So-too has my 48" twist .40 cal. Goodioen barrel.

I think the key, is to find the accurcy load for YOUR barrel and not worry about the inches of twist in a .45, as long as it has between 45" and 65". I dare say, there is a load combination that will shoot the same, if the twist was 80" - you need only to find it.

[Hungry Horse]

The cal./twist combination that got a lot of this thinking started in modern times, is the .40 cal. 1 in 48" barrels. It seemed back then, with all things considered, it was pretty hard to out shoot one of these combinations. A lot of barrel makers started doing research,or rediscovering 19 century research,  on twist/caliber and accuracy. I think, the findings went something like this. .40 cal. 1-48", .45 cal. 1-56", .50 cal. 1-60", .54 cal. 1-66" and so on. Most old time gunsmiths didn't bother changing the twist because most guns weren't "target rifles" they were hunting guns, or used for protection.

                          Hungry Horse

[Gaeckle]

The cal./twist combination that got a lot of this thinking started in modern times, is the .40 cal. 1 in 48" barrels. It seemed back then, with all things considered, it was pretty hard to out shoot one of these combinations. A lot of barrel makers started doing research,or rediscovering 19 century research,  on twist/caliber and accuracy. I think, the findings went something like this. .40 cal. 1-48", .45 cal. 1-56", .50 cal. 1-60", .54 cal. 1-66" and so on. Most old time gunsmiths didn't bother changing the twist because most guns weren't "target rifles" they were hunting guns, or used for protection.

                          Hungry Horse

I agree with most of htis statement......differnces in twist is a modern item and then the question becomes what is modern? Pointed projectiles take different twists than does a roundball.

I love picking up old original barrels and there is one common denominator that I have found in these old barrels and that is twists by our standards are quite slow.....even with small 30 calliber barrels.

My guess (and it is only a guess) is that the man owning the rifling bench had just one lead or twist and every barrel he rifled had the same twist. There is a lot of work that goes into making a lead or part that imparts a twist. I also think that one gunsmith's twist would be his signiture, in a matter of saying, and would be used to gain customers. It may also be that the concept of breachloading cartridge guns was something akin to airplanes and the barrel would be rifled with the idea that it could always be increased in diameter and rifled again.
 
By today's standards, we can have just about any pitch we want. Back then it could well have been that this is the pitch, now go figure out the load by practice and manipulate patch and powder.

[northmn]

I ordered a 1-33 twist in a 33 cal barrel as I wanted to see if that would permit slightly lighter loadings for a small bore.  In larger bores the old rule of thumb was the slow twists gave more accuracy with heavier loads (modern thinking)  Another issue is that many feel the slower twist does not foul as bad or is not as affected by fouling as in gain twist barrels taht were slow at the breech and speeded up at the muzzle.  I have never seen these rules of thumb substantiated as many target shooters claim exceptions.

DP

[Candle Snuffer]

I took the opposit road some years back Dpeck, and had Ed Rayl make me a .40 & .45 caliber barrel(s) with 1-72 twist.  Both shoot very accurate with 40 & 45 grains of 3f as well as 60 & 65 grains of 3f.  Even tried 75 grains of 3f in the .40 a few times with excellent results.  Had to put newspaper between the patch & ball with that 75 grains so the patch would hold.

However, for the most part I'm shooting the Green Mnt Brls; .40 x 1-48, .45 x 1-60, .50 x 1-70, .54 x 1-70...  As Daryl said, just have to
find the right load for each barrel.  Even though I've found them for each of the above barrels - I'm always tinkering with loads with all of them.

[camerl2009]

too many varyables like velocity,bullet diameter,bullet length and bullet material/alloy

http://kwk.us/twist.html i use this often