Spin Drift?

[Bigcat_hunter]

Ok so I'm shooting a 300 RUM, Berger 210 VLD's at 2870 fps. At 700 yards I start to get the bullet impact to the right. I have to hold 1 MOA @ 800 yards, 2 MOA @ 900 & 3 MOA @ 1000 yards. This is in a no wind situation.

I double checked my scope tracking with a plum line at 100 yards and my scope is perfectly aligned with the bore.

I don't know if it matters but I am shooting at a range that points east (in case the rotation of the earth has anything to do with it). Could this bullet impacting to the right be caused by spin drift? Any ideas?

 

[Broz]

It would most likely be that the scope needs rotated because as you dial it up it is not following the plumb line. Did you shoot the line test to make sure it is indeed tracking true?

Spin drift should be close to 1/2 moa for that rifle and load at 1000.
East and west would have a greater effect on elevation than windage.

3 moa at 1000 is a lot. There is a problem still.

Jeff

 

[Bigcat_hunter]

It would most likely be that the scope needs rotated because as you dial it up it is not following the plumb line. Did you shoot the line test to make sure it is indeed tracking true?

Spin drift should be close to 1/2 moa for that rifle and load at 1000.
East and west would have a greater effect on elevation than windage.

3 moa at 1000 is a lot. There is a problem still.

Jeff

Maybe I bobbled a little while shooting the plumb line but it appeared to be on the line at zero and on the line at 20 MOA up. The scope must be rotated to the left just a hair. I didn't check the actual measurement, I was just checking to see if the reticle was plumb.

 

[Bigcat_hunter]

It would most likely be that the scope needs rotated because as you dial it up it is not following the plumb line. Did you shoot the line test to make sure it is indeed tracking true?

Spin drift should be close to 1/2 moa for that rifle and load at 1000.
East and west would have a greater effect on elevation than windage.

3 moa at 1000 is a lot. There is a problem still.

Jeff

You were correct. I went to the range this morning and re-zeroed my scope. It took about 20 rounds of rotating, re-zeroing and tracking. Finally after 400 rounds and two scopes later my rifle is ready to hunt. Attached is a picture of a 1000 yard group.gun)

 

[Broz]

Great!! I am glad to see you got her up and running. Nice group too.

Jeff

 

[Archery1973]

Broz is a wealth of good info and that is a serious 1000 yard group.