Twist direction?


July 22, 2007, 10:42 PM
Since this pertains to rifles, handguns, and slug barrels, I figure I might as well post it here.

What difference (if any) does the direction of the twist in rifling make? (i.e. How is 1:16 RH different in performance from a 1:16 LH?)


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July 22, 2007, 10:50 PM
You get some torque but not enough difference for most people to notice.

Standing Wolf
July 22, 2007, 10:53 PM
It either goes thisaway or thataway. As long as you're not on the business end of it, it doesn't matter; conversely, if you're on the business end of it, you probably aren't going to care longer than about a tenth of a second.

Seriously: I believe the direction of twist makes no discernible difference. I heard that from an old guy who used to teach physics quite a few years ago.

July 22, 2007, 10:54 PM
I don't think it makes any difference at all.

The only analogy I can think of right now is direction of rotation of an internal combustion engine. The "standard" direction of rotation for an engine is counter clockwise looking at the end of the crankshaft where the power comes out of the engine (like where the clutch or transaxle or transmission would go). There are, however, some cars that have "backwards running" engines, where the crankshaft is running clockwise - like most if not all Hondas. Hondas seem to work just fine with their wrong running engines.

July 22, 2007, 10:54 PM
From what I understand, the direction of twist in a handgun is so that it will torque (even slightly) into a right-handed person's hand, as opposed to out of the hand - for better control. I saw a 1911 somewhere recently that was set up for a southpaw - it was an exact mirror-image, even down to the direction of twist inside the barrel.

July 22, 2007, 10:57 PM
On a practical difference. It will change the direction that the bullet drifts, assuming zero wind...which is pretty rare. A RH twist will cause the bullet to drift slightly to the right. It doesn't amount to much. Maybe a quarter-inch or so per hundred yards, depending on the bullet shape, mass, velocity, etc...but a slight breeze in the opposite direction could easily counteract it.

It will cause the rifle to recoil differently, which may have more of an influence on the bullet strike than the drift. Since the gun is in recoil before the bullet leaves the barrel, whichever direction the rifle moves the shooter when it kicks will affect the bullet's path. Some people move more than others under a rifle's this won't be a constant that you can calculate. It's also why each shooter should zero his own rifle. Only rarely
will a rifle zero the sasme for two different people.

With pistols, it can make a more noticeable difference. The 1911 pistol has a LH twist. This causes the gun to torque into the palm of the right hand under recoil..keeping it more stable. If you fire the gun in the left hand, it will torque away from the palm, which is less stable...and the gun will arc and
turn almost horizontal unless you have a very firm grip on it. Using two hands negates the tendency a lot.

July 23, 2007, 12:01 AM
silly kids... clockwise twist north of the equator, and counter-clockwise twist south of the equator, just like the loo

July 23, 2007, 12:11 AM
About the only reason I can think that direction of twist might matter is if the twist rate is fast and the weapon is light (like a handgun). You'd probably want twist in the dirtection that tends to tighten the barrel in the frame, rather than loosen it. But that's only supposition. I think twist direction is mainly a matter of tradition.

Why do Smith and Wesson revolvers turn counter-clockwise and Colts turn clockwise?

July 23, 2007, 04:30 AM
Taliv got it right, here....

July 23, 2007, 04:31 AM
guntech, answer is ... jealousy.

July 23, 2007, 03:17 PM
I work on and deal with alot of 9mm Berettas. The Beretta barrel has a right hand twist and according to Beretta this is why the left side locking block breaks. Remember physics "for every action there is an equal yet opposite reaction". If this holds true a gun with a barrel that twists right should torque to the left or away from the right hand. I sometimes perform shooting demonstrations. I can tell you I have shot one handed with minimal grip on the gun and have never had it twist out of my hand. The only felt twist is the felt upward recoil.

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