Is Your Rifle Scope Canted?

[Wynne Echols]

Britt brought something to my attention the other day that I think is worth sharing. I am sure that many of you good shooters are aware of this, I was not, therefore I am sharing in hopes that someone will learn something that will improve their shooting. At my last benchrest match, June, I did not notice any condition at the 500 yard target and did not dial any windage adjustment into my scope. When the target was scored, the group had formed to the right of center for no apparent reason. The group was far enough right that it caught my attention.

Fast forward to this past Friday, I go to Reese Bottom a little after 6, perfectly still conditions, in search of a 520 yard dope so that I would be prepared to shoot in B’ham on Saturday. The rifle barrel was clean and after 5 shots it settled in and shot 3 straight bullets in the exact same hole at 100 yards. Still condition, + 8 moa at 520 yards, and the dasher shot 3 in .750″ but was 3″ right of center.

I was telling Britt about my experience and even accused Reese Bottom of having haints. He mentioned that my rifle scope was probably canted which would force the scope to track off center as it goes up From 100 yards to 520 yards and a 8 moa adjustment the scope moved 3″ right with 0 windage adjustment which I think helps explain why the June 500 yard group formed to the right.

I have all kinds of bubbles, levels, and other stuff, but I have a hard time believing any tools made can completely straighten the crosshairs. Some of you good shooters prove me wrong. I do not believe that this is a death move, but it is a situation that the shooter needs to be aware of[dialing windage with no windage adjustment]. Paying very close attention to sighter shots[I did not in June] can avoid the situation. Sorry for the length. Tell me I am crazy or tell me how to correct it. Thanks for reading, WWE

[Anonymous]

For what it’s worth. I set our guns in their shooting positions, whether that be bipod or mechanical rest. I took a piece of poster board at 100 yards and while it was on the backer, used a 4 foot level and drew a vertical line from top to bottom on the white poster board. I then looked through the scope while holding the rifle in my shooting position and lined up the vertical crosshair with the vertical line. That’s where I tightened my scopes down. While they were in that position I also leveled to bubbles on the scope. That was the hard thing to get right and may actually still be just a bit off.

[Wynne Echols]

Dan, I used your line, but looking back, I used the line and probably should have used the edge of the line. Best I remember it was a felt pen line that was fairly wide. Steve has made a good suggestion below. Thanks for the comment. WWE

[Anonymous]

Dan I have used the same procedure but at 300 yards. Level gun on bench and crosshairs on line drawn vertical with the level. I like to then set up a paper with the plumb line as far down range as I can and Put a target dot at bottom of line and shoot a group. Dial scope up as many minutes as possible to stay on paper and shoot another group holding on the same target dot at bottom of line. See if group goes left or right. If so the scope is not tracking straight up and needs to be adjusted in rings again. Hope this makes sense!

[Wynne Echols]

Steve, do you care to share with everybody the method you use to level your rifle? Thanks for sharing the above. WWE

[Anonymous]

Wynne I was also thinking and assuming your zero was exact. If the 6mm (.243) group was only a bullet width to the right, that would be 1/4 MOA. You stated that at 520 you were 3″ off center. That could have been 1/2 a bullet hole off at 100. Again, I was assuming the 100 yd zero was exact.

[Anonymous]

Sorry Wynne, my math was off. It wouldn’t have been that much error in 1/4 MOA. thinking too fast I guess…lol

[Anonymous]

Great info Steve. I like how you checked the tracking, I’ll use that myself real soon. Thanks

[Dave Burkart]

Wynne, that is certainly a good point. When I setup at Williamsport, 1000 yd., I try to always remember to lay the cross hair on the top edge of the target backer and level adjust the level so it is square to the backer. Otherwise the tracking does not stay straight. When I forget to do this it is generally quite apparent in the size of the group I shoot.

[Wynne Echols]

Now that makes a little more sense. Question, has the club taken extra measures to make sure the backers are level? That might be something that we could do to refresh Reese Bottom. I do know that not much effort was put into leveling the backers. Thanks Dave, always enjoy your interesting input. WWE

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