Long Range Hunting Online Magazine

Go Back   Long Range Hunting Online Magazine > Rifles, Reloading, Optics, Equipment > Rifles, Bullets, Barrels & Ballistics

Rifles, Bullets, Barrels & Ballistics Applied Ballistics


Right Hand Twist/ POI

LinkBack Thread Tools Display Modes
Unread 09-06-2006, 08:14 PM
Platinum Member
Join Date: Jan 2005
Location: Pocahontas, AR
Posts: 1,034
Right Hand Twist/ POI

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.
You will not make peace with the Blue Coats, you are free to go.
Reply With Quote

Unread 09-07-2006, 12:11 AM
Gold Member
Join Date: Sep 2003
Location: Blighty
Posts: 637
Re: Right Hand Twist/ POI


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

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.

Itís not yaw, but precession caused by the bulletís 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.

[/ QUOTE ]

...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. 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.

[/ QUOTE ]

Have a look at
Reply With Quote


Thread Tools
Display Modes

Similar Threads for: Right Hand Twist/ POI
Thread Thread Starter Forum Replies Last Post
Custom Left Hand Rifles - 4 to 6 week completion times on left hand rifles Len Backus Rifles, Bullets, Barrels & Ballistics 105 12-17-2012 11:24 PM
Left Hand LA 700 in Right Hand Stock benchracer Gunsmithing 7 07-09-2010 08:16 AM
LEFT HAND OR RIGHT HAND Surveyor The Basics, Starting Out 13 12-14-2008 07:29 PM
RCBS APS Hand primer & Lee Hand primer accuratebrass Reloading Equipment and Components 2 12-07-2008 02:54 PM
right or left hand twist? bigsal5353 Rifles, Bullets, Barrels & Ballistics 11 05-05-2004 08:16 PM

All times are GMT -5. The time now is 10:17 AM.

Powered by vBulletin ©2000 - 2016, Jelsoft Enterprises Ltd.
Content Management Powered by vBadvanced CMPS
All content ©2010-2015 Long Range Hunting, LLC