Replacing barrel in my Kimber 9mm. The factory barrel is a LH twist and the Wilson replacement is a RH twist. Twist rate seems about the same. I was wondering if there is any noticeable difference in the direction. I havent shot the Wilson yet so I cant comment. I also have never noted with my other handguns the direction of the twist.
Rifling twist direction
- Thread starter BoogieMan
- Start date
waveslayer
New member
you will be fine, just if you shoot long range your drift will be the opposite but not likely with a handgun round.
BigMikey76
New member
At hand gun distances, you will not notice a difference.
The "shooting north or south" refers to the Coriolis Effect, which has to do with the turning of the Earth, not with something so insignificant as the bullet drift cause by the rifling twist in a handgun. At one time, a company making reloading equipment claimed that the Coriolis Effect cause wide groups and that their products would "fix" the problem. Absurd, of course, but they just hoped that none of the readers of the ad knew what the Coriolis Effect was.
FWIW, the maximum deflection caused by the Coriolis Effect on a rifle bullet is less than two inches at 1000 yards. No, you can't claim that the Coriolis Effect caused you to miss that deer at 50 feet!
Jim
FWIW, the maximum deflection caused by the Coriolis Effect on a rifle bullet is less than two inches at 1000 yards. No, you can't claim that the Coriolis Effect caused you to miss that deer at 50 feet!
Jim
The bullet drift actually caused by the rifling is of interest to long range rifle shooting, though. Take a look at the Model 1905 sight on the Model 1903 Springfield, and you will see that the cut in the sight leaf is slanted; that is to make up for the bullet drift, which is pretty much a constant. But as noted, for handguns, the drift is not important, and the only thing usually noticed about rifling twist is the twist of the gun in the hand.
Jim
Jim
Coriolis effect is not a constant it is a variable dependent upon the latitude that you are at. It is more pronounced near the equator than it is near the poles. Rifling drift can be more or less depending on the direction of turn vs. N. / S. hemisphere and ranges involved. This is something that becomes very important at naval rifle distances esp. when T.O.F. is measured in 20 sec. or more intervals.
rifling direction
I remeber back in basic training, Army, many years ago a firearms instructor told me that the 1911's had rifling that was diferent than most weapons. The reason being that the pistol would kick back into a righthanders grip rather than try to kick out of your grip. Sounded reasonable to me except that I am left handed. I still shot it well.
I remeber back in basic training, Army, many years ago a firearms instructor told me that the 1911's had rifling that was diferent than most weapons. The reason being that the pistol would kick back into a righthanders grip rather than try to kick out of your grip. Sounded reasonable to me except that I am left handed. I still shot it well.
g.willikers
New member
Just shoot it upside down.
DAVID NANCARROW
New member
I think the only thing you are going to notice is that your grip will try to torque the opposite direction than what you are used to. Other than that, the recoil is going to be about the same.
Hi, SHR970 and JimPage,
The opposite; bullet drift caused by rifling is a constant (other things can affect it), while the Coriolis Effect varies depending not on the latitude of the shooter but the latitude of the shooter and the latitude of the target as well as whether the direction of fire is due North-South or in some other direction. It is a reflection of the fact that in a long range gun, firing on a spherical, rotating globe (Earth), the difference in latitude will mean that the shooter and the target have different rotational velocities. A shooter at the Equator, firing due North, is not moving Eastward as fast as is his target in, say, Chicago. So no matter how carefully the marksman aims, he will always miss the target unless he takes the Coriolis Effect into consideration.
Weather is affected by the Coriolis Effect, which is why hurricanes coming out of the Florida area curve to the East as they move north. It is also why the continents themselves are slanted to the East in the Northern hemisphere and to the West in the Southern - look at a map of the Americas and East Asia (China-Japan) to see what the Coriolis Effect did to the earth itself.
But it won't make you miss that target on the local range.
Jim
The opposite; bullet drift caused by rifling is a constant (other things can affect it), while the Coriolis Effect varies depending not on the latitude of the shooter but the latitude of the shooter and the latitude of the target as well as whether the direction of fire is due North-South or in some other direction. It is a reflection of the fact that in a long range gun, firing on a spherical, rotating globe (Earth), the difference in latitude will mean that the shooter and the target have different rotational velocities. A shooter at the Equator, firing due North, is not moving Eastward as fast as is his target in, say, Chicago. So no matter how carefully the marksman aims, he will always miss the target unless he takes the Coriolis Effect into consideration.
Weather is affected by the Coriolis Effect, which is why hurricanes coming out of the Florida area curve to the East as they move north. It is also why the continents themselves are slanted to the East in the Northern hemisphere and to the West in the Southern - look at a map of the Americas and East Asia (China-Japan) to see what the Coriolis Effect did to the earth itself.
But it won't make you miss that target on the local range.
Jim
Hi, D Thompson,
I have heard that story also. The truth is that the M1911 has left-hand rifling because Colt's rifling machines were set up that way for no special reason. Other stories in the same category are the "even a near miss from a .45 will kill instantly", a silk handkerchief will stop a bullet from a .45", and "if someone pulls a .45 on you, just stick your finger in the barrel and the gun will blow up without hurting you." Don't bet on any of those.
Jim
I have heard that story also. The truth is that the M1911 has left-hand rifling because Colt's rifling machines were set up that way for no special reason. Other stories in the same category are the "even a near miss from a .45 will kill instantly", a silk handkerchief will stop a bullet from a .45", and "if someone pulls a .45 on you, just stick your finger in the barrel and the gun will blow up without hurting you." Don't bet on any of those.
Jim
g.willikers
New member
Sounds like tests for Mythbusters.
Are they still on tv?
Are they still on tv?
Coriolis Effect: For those who may be interested in numbers:
A point on the face of the earth moves east at a rate of 900 knots times the cosine of the point's latitude.
Assume a shooter at 41-34 (say, in New England). 41°-34' = 41.566667 degrees; the cosine of that is 0.7481842071; the speed at which our shooter is moving is 673.3657864 knots, or 765.1883937 mph, or 1122.276311 fps.
Now assume our shooter is aiming at a target that is 1000 yards due north (true north) of him. 1000 yards change of latitude is 0.5 minute, so the latitude of the target is 41.575000 degrees. The cosine of this is 0.7480876984. The rate at which the target is moving east is 673.289285 knots, or 765.0896915 mph, or 1122.131548 fps.
This means that the target is moving east 0.1447631692 fps slower that the shooter, or 1.737715803 inchs per second.
Assume time of flight of flight of the bullet is an even second, this means that our shooter should lag the target by 1.73 inches, which is 0.167 MOA.
Within the noise.
A point on the face of the earth moves east at a rate of 900 knots times the cosine of the point's latitude.
Assume a shooter at 41-34 (say, in New England). 41°-34' = 41.566667 degrees; the cosine of that is 0.7481842071; the speed at which our shooter is moving is 673.3657864 knots, or 765.1883937 mph, or 1122.276311 fps.
Now assume our shooter is aiming at a target that is 1000 yards due north (true north) of him. 1000 yards change of latitude is 0.5 minute, so the latitude of the target is 41.575000 degrees. The cosine of this is 0.7480876984. The rate at which the target is moving east is 673.289285 knots, or 765.0896915 mph, or 1122.131548 fps.
This means that the target is moving east 0.1447631692 fps slower that the shooter, or 1.737715803 inchs per second.
Assume time of flight of flight of the bullet is an even second, this means that our shooter should lag the target by 1.73 inches, which is 0.167 MOA.
Within the noise.
Nice math and the same answer, but to get back to the subject of the thread, the rifling twist has nothing to do with the Coriolis Effect, while it does affect the much greater bullet drift. Given the same rifle, the rate of drift will be pretty much a constant and the sights can be made to compensate for it. The Coriolis Effect varies with the latitude and direction of fire, so unless soldiers can always arrange to be firing in the same direction, no sight adjustment can compensate.
Jim
Jim