Rotational Spin-Drift with 8 twist 6-06?

[BD100]

Hello All,

I've finally been able to run my new 6-06 out to 400 and 500 yards and have noticed my groups are consistently right of center beyond the 300 yard mark. It impacts appx 1.5-2.0 inches right at 400 and 2.5-3.0 inches at 500. All groups from 100-300 are dead center. It's not until after 300 they start impacting to the right.

Specs on my gun and load are as follows...

6mm-06
26 in, 8 twist barrel
105 Berger VLD
Velocity-3300
Bullet RPM-Appx 300,000 rpm.
Calm winds, verified with wind flags

Is this a common phenomenon when spinning bullets that fast? I've been loading for about 6 years, but this is my first experience with a fast twist barrel and higher velocities.

Thanks in advance for any input.

 

[Nomad47]

Click on this link http://www.jbmballistics.com/cgi-bin/jbmtraj_drift-5.1.cgi
and put in your numbers and zero wind. Whatever the program tells you for scope windage correction at 500 yards multiplied by 5 is the amount of actual spin drift.
HTH.

 

[ronemus]

Spin drift is usually smaller than that (approximately 1MOA@1000 yds). Are you using a level on your rifle? If the rifle is canted, a short range zero will have your groups walking to one side at long range. A ievel needs to beset up so the scope is directly above the bore. If you're not using a level,you probably should.

 

[MrMajestic]

Spin drift is usually smaller than that (approximately 1MOA@1000 yds). Are you using a level on your rifle? If the rifle is canted, a short range zero will have your groups walking to one side at long range. A ievel needs to be set up so the scope is directly above the bore. If you're not using a level,you probably should.

What he said....

 

[FeMan]

As said above, make sure your rifle is plumb and if your scope is tracking true. 1.5 degrees of cant has about the same impact on drift as spin. Without knowing your MV, BC, elevation, and atmospheric conditions it isn't possible to check your spin drift, but you should be around 0.75" at 400, 1.25" at 500. At 1000 you will see somewhere around 6 inches.

 

[BD100]

Good info! Thanks all.

Sounds like I need to check the scope. It was mounted by the gunsmith who built the rifle, so I have no idea
if a level was used or not. Sounds like it might be the culprit. I'm using a Zeiss Conquest 4.5-14 with a Rapid Z800. It's zero'd for 200 yards.

 

[FeMan]

I have a couple Zeiss scopes on hunting rifles and found the to track fairly well. If you are dialing ranges, make sure the vertical is tracking true as well. You can do that at 100 yards by using a consistent aim point and shooting groups dialing up 10 moa at a time and making sure the groups are not drifting. Make 100% sure your scope is level with the action first though.

 

[Toolbreaker]

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