Right Hand Twist/ POI

[Nomosendero]

I think this has been discussed in the past, I tried the search function & could not find it. This is a silly question but I want to put it to rest. I have heard for years that if a barrel has a right hand twist the bullet will drift very slowly to the right. When I was a kid I remember Elmer Keith saying that he sighted his rifles 1/2"
to the left so that at 5-600 yars it would be slightly right.
In more resent times I have had it explained to me that
the bullet would fly straight whether shot out of right or left hand twist & only will veer as velocities drop & bullet begins to yaw & becomes unstable & then of course it
can veer in any direction. Sorry for the silliness, I just want to put it to rest, the second idea seems logical to me.
Thanks!!!

 

[Brown Dog]

nomosendero,

This got discussed a bit a couple of months back; short answer is, yes -right hand twist gives drift to the right:

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Drift (or spindrift) is one of the few 'weird and wonderful' ballistic effects observable and measurable at 1000yds...the others (coriolis etc) are all at play, but not measurable. Drift absolutely is.

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It's not yaw, but precession caused by the bullet's tip continuously pointing down as its spin axis stays parallel to the trajectory path. As the bullet noses over, its right-hand twist causes it to change its direction to, or drift to the right.

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...actually, projectiles fly slightly nose up in relation to their trajectory; this means that air resistance will try to lift the projectile's nose. Because the projectile is a powerfully spinning gyroscope it reacts to this upward pressure by yawing slightly to the right (it's just something gyroscopes do), with this new yaw, the changed direction of air resistance causes the nose to move down (again, because of the weird way gyroscopes react to forces)...then it will move left...then it will move up ....and so on round and round.
This creates an effect known as 'nutational rotation' ..a more complex movement than I can describe without drawing a picture.
....anyway, the net effect of all this movement is that (clockwise spun) projectiles average a 'nose high and right' attitude in relation to the line of their trajectory. This 'average orientation' of the projectile known as the yaw of repose. ...it should be obvious why a 'high and right' yaw of repose (also known as 'equilibrium yaw') will cause increased air pressure on the left side of the projectile and thus cause it to drift to the right.


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Have a look at http://longrangehunting.com/ubbthreads/s...part=1&vc=1