svtruth
Member
Are there any reasons to have rifling twist one way or the other?
Twist Direction
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rcmodel
Member in memoriam
Colt thought so.
They historically used left hand twist.
Just about everyone else used right hand twist.
One theory is that after the Colt factory burnt down, production was moved to England for a while and the English used left hand twist??
Another is that they used left hand twist to cause the recoiling gun to torque into the right handed shooters grip.
In actual fact, it makes no accuracy difference one way or the other on a rifle as far as I know.
rc
They historically used left hand twist.
Just about everyone else used right hand twist.
One theory is that after the Colt factory burnt down, production was moved to England for a while and the English used left hand twist??
Another is that they used left hand twist to cause the recoiling gun to torque into the right handed shooters grip.
In actual fact, it makes no accuracy difference one way or the other on a rifle as far as I know.
rc
Standing Wolf
Member in memoriam
It's a secret. Even physicists and the president of the United States can't be trusted with it. Lee Harvey Oswald stumbled upon a small part of the truth, and you know what happened to him, right?
Trust me, please: you really don't want to know.
Trust me, please: you really don't want to know.
Cop Bob
Member
That pretty much sums it up... and that's about all I have to say about that!
hirundo82
Member
It's due to the Coriolis effect. Barrels made in the Northern Hemisphere have a right-hand twist, while those made in the Southern Hemisphere have a left-hand twist. Few people know that companies that make shotgun barrels have to locate their manufacturing facilities precisely on the equator to avoid having any twist to their barrels.
No, not at all.
kingpin008
Member
Well played, good sir. Well played. 
well i hate to be the one to step aside of the mickey mouse garbage and actually attempt to answer the OP's question, but...
the external ballistics of any handheld weapon that i know of could not possibly be measurably affected by whether the barrel is rifled RH or LH. i'm not standing upon any sort of scientific database here, but the external ballistics of a fired round, through a rifled barrel, can't possibly be altered that much by whether your toilet flushes clockwise or counterclockwise.
the external ballistics of any handheld weapon that i know of could not possibly be measurably affected by whether the barrel is rifled RH or LH. i'm not standing upon any sort of scientific database here, but the external ballistics of a fired round, through a rifled barrel, can't possibly be altered that much by whether your toilet flushes clockwise or counterclockwise.
MachIVshooter
Member
It's arbitrary, and has no effect on accuracy or recoil characteristics. The amount of torque generated by the rotating bullet is very miniscule, and spin drift occurs at range no matter which direction the bullet is rotating.
svtruth
Member
Thanks all!
Very educational, as always.
Very educational, as always.
NCsmitty
Member
As http://en.wikipedia.org/wiki/External_ballistics indicates, RH twist barrels will spin drift (Gyroscopic drift) to the right, and LH twist will drift left.
Coriolis drift effect in the northern hemisphere makes the projectile appear to curve over to the right due to the earth's rotation.
So theoretically, a LH twist can offset the Coriolis effect in the northern hemisphere by some degree.
Long range artillery computations will take these effects into account, when plotting targets
Wikipedia doesn't always have it right, but can be a quick reference for many subjects, and usually understandable.
NCsmitty
Coriolis drift effect in the northern hemisphere makes the projectile appear to curve over to the right due to the earth's rotation.
So theoretically, a LH twist can offset the Coriolis effect in the northern hemisphere by some degree.
Long range artillery computations will take these effects into account, when plotting targets
Wikipedia doesn't always have it right, but can be a quick reference for many subjects, and usually understandable.
NCsmitty
A spinning ferromagentic object is going to create a magnetic field. Iron, cobalt, nickel, bismuth, ytrirrium, managanese, and a few heavy metals. Is there enough of any of these in your round to make a difference? If there is, the magnetic field will interact with the iron in your barrel. That interaction might have some infintesimal effect on trajectory.
Right hand twist = current in the direction the bullet is going.
Right hand twist = current in the direction the bullet is going.
KodiakBeer
member
If you're a reloader, you can just seat your bullets backwards if you have a gun with the wrong twist.
MachIVshooter
Member
Most bullets do not contain ferrous metals.
Hypnogator
Member
Interesting Observation re: Colt Barrels
Early in my career in CID, agents were issued either a Colt Detective Special or a S&W Model 10 with 2" bbl. The Smith barrels were pinned in place, while the Colts weren't. Occasionally, some Colt users would experience shot groups that started to wander to the right, because the torque of the bullets being fired began unscrewing the barrels!
The armorers were usually able to fix them handily, but I always preferred the slightly heftier Smiths.
Early in my career in CID, agents were issued either a Colt Detective Special or a S&W Model 10 with 2" bbl. The Smith barrels were pinned in place, while the Colts weren't. Occasionally, some Colt users would experience shot groups that started to wander to the right, because the torque of the bullets being fired began unscrewing the barrels!
The armorers were usually able to fix them handily, but I always preferred the slightly heftier Smiths.
It may have something to do with the machining capability of manufacturers. I don't know any specifics but it may be more convenient to machine a right hand twist than a left hand twist.
Interesting trivia- metric FAL flash hiders thread onto LH threads so that the force of the "spinning" gases behind the barrel force the flash hider on tighter, as opposed to loosen it.
Interesting trivia- metric FAL flash hiders thread onto LH threads so that the force of the "spinning" gases behind the barrel force the flash hider on tighter, as opposed to loosen it.
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