Does rifling twist direction matter?

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Dingoboyx

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I just had a weird thought (yup, another one I hear you all moan):barf:

However, I will go on, regardless....:D

Water goes down the drain clockwise here down south of the equator, up where you guys are, it goes down anti clockwise (I would love to see that) I have spoken with some serious boat racers who race in both hemispheres, they actually can get cranks, cams & props to reverse run engines/props because it makes a wee difference in performance.... that got me wondering... does the direction of rotation of a bullet matter? Does a projectile spinning the same direction as the weather systems in each respective hemisphere, make it more or less accurate than a projectile spinning against the natural (for that hemisphere) direction? Have any of you guys got 2 rifles or HG's the same except opposite twist to each other? Is one more accurate than the other? Or is there no difference (or the difference is immeasurably small?:confused:

Hopefully some of you science guru's might know? An interesting thought, I thought, at least?
 
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Tom2

New member
I was under the impression that Colts and Smiths had rifling in opposite directions but there are so many factors in the accuracy that neither brand gun can demonstrate any superiority over the other in practical terms, that I can imagine. Or is it that their cylinders rotate in opposite directions? I forget, maybe both. One individual specimen of each model is gonna be slightly different than the other. Just due to variances in tolerances. In that case I would merely tightly hold onto any particular gun that proves to have excellent accuracy in any case, let the ones that don't quite measure up become trade goods, and pop the top off a Fosters and relax. Perhaps it is a factor of microscopic theoretical significance, perhaps inquire to a NASA scientist. Might affect the trajectory of some satellite by a few feet or something. I cannot see some miniscule global effect doing much to a bullet in it's short flight of between a few milliseconds to a second or two. Now if you were shooting bullets in orbit that kept going and going...... Now it is time to pop the top off the second one and forget all about this!
 
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Maser

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Think of throwing a football. Two guys throw the ball in a perfect spiral, same strength and trajectory, but one throws right handed and the other throws left handed causing the balls to spin in opposite directions. Gravity will make them both fall at the same rate. I'm no physics major nor do I claim to be, but that's my theory on the subject.
 
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Hank D.

Moderator
Does twist direction matter?

As far as I know both S&W and Colt have the same direction twist In the barrel rifleing, On the other hand, the cylinders on the colt revolver turn clockwise and counter clockwise on the S&W This I know because of a true story that I heard many years ago about two New York City cops In a bar playing with of all things there guns! They both had snub nose revolvers, one a Smith and the other a Colt. Now the two Wize Kids were playing Russain Roulette and knot knowing this fact about which way the cylinder turned on what gun, one of New Yorks finised blew his brains all over the bar!!! This is a true story that happened in Washington Hights, In N.Y.C. In the early 50s, I saw the story In either the Daly News or the now defunked N.Y. Daly Mirror. I think this Is a good lesson on knowing how you gun works, and I'm sure that all the people out there that have both a Colt and a Smith that do not know this fact are checking this out right now!!! F.Y.I. Hank D.
 
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sundog

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Harry Pope thought so, that's why he made left hand twist. For a right hand shooter the rifle would torque back into the shoulder and cheeck, thus producing more stability. Does it really matter? How good a shooter are you and how good is your equipment?
 
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chris in va

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I see what you're getting at, Coriolis effect and all that. I suspect it would take a very long shot, 800+ meters (metres?;)) to see any change.
 
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SteelJM1

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"Water goes down the drain clockwise here down south of the equator, up where you guys are, it goes down anti clockwise (I would love to see that)"

Actaully not true. The direction that water turns down a drain has mostly do do with the geometry of the drain, not the almost nonexistant coriolis effect on it. The only way you'd see coriolis in a firearm if you were shooting N-S or S-N and it was a vary long shot, and the bullet was moving slow. And even then you could probably not be able to measure the effect. Maybe with cannon shooting miles and miles it has to be taken into effect.
 
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Keltyke

Moderator
does the direction of rotation of a bullet matter?
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Only if you remove your aluminum foil helmet and face to the East when shooting.

SteelJM1 - Thanks for a modicum of truth amongst all the fantasy. A bathtub drain is just a little different than a 200-mile-across hurricane.
 
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Microgunner

New member
No Dingoboyx,
Bullets don't even need to rotate at all up here to be accurate. Amazing but true. Just one of the many benefits of living in the northern hemisphere.:D
 
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JohnKSa

Administrator
There is no practical effect on small-arms accuracy due to the Coriolis effect. Long range artillery guns (guns with a practical range in miles) have to make corrections for the effect.

The direction of rifling twist doesn't affect accuracy, but it does have a small effect (small enough that it's not really practical to consider it) on vertical point of impact at long ranges when shooting in a crosswind.
 
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A/C Guy

New member
The correct answer is....

does the direction of rotation of a bullet matter? Does a projectile spinning the same direction as the weather systems in each respective hemisphere, make it more or less accurate than a projectile spinning against the natural (for that hemisphere) direction?
Click to expand...
Yes!
It has a measurable effect on bullets. The amount is dependent on the duration of the flight of the projectile. The military is aware of it's effect on missiles and long range guns.

This subject was once discussed at www.longrangehunting.com

The physics of it are fairly well known and not complicated.

For your 300 yard shot with your .30 caliber rifle, the effect is a fraction of an inch, but we really don't notice or realize it because of the influences from the wind. You would have to have an absolutely dead calm day with ZERO wind to even measure it, if you had 2 rifles accurate enough to give you .1 MOA accuracy to eliminate all other variations of the POI

Good topic for theoretical discussion at the campfire.
 
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BitterClinger

New member
Direction of twist, hemisphere effects

Yes, yes, oh my gosh yes. The direction of twist and your hemisphere will have an effect on your ballistic trajectory. 99% of shooters will not know this because it is one of two MINOR effects acting against your ballistics and they can only be observed at very long range. GYROSCOPIC DRIFT: Right-hand twist will cause a bullet to drift right. Left-hand twist, left drift. CORIOLIS ACCELERATION: LATERAL: Farther North of equator yields more right drift. South yields left. VERTICAL: Firing toward the East yields lift. West yields drop. This effect is maximized at the equator and is null at the poles.
Check out http://www.appliedballisticsllc.com/index_files/SpinandCoriolisDrift.html
 
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