Rifle cant and scope cant.

[dthunter]

This topic continually comes up and for the most part is sufficiently figured out.
People tend to sweat the small stuff so much that they no longer trust thier set up.

I have posted many times on this subject and have learned a few things.
1.) first order of importance, understand that variables( cant,wind,thermals,personal movement, poor trigger control and release, etc) and normal shot variences will always cloud a persons results to a degree.

2.) i have found that leveling the fire arm in the vertical plane is of minimal importance. BUT has an effect of comfort and repeatability.

3.) the scope/crosshairs & vertical adjutsments must travel in the vertcal plane "ONLY" to be effective.

4.) align the vertical crosshairs to be parrellel with a plumbob line at what ever distance a perfectly clear image of the plum line is visible. I use 100yds.
Then while holding the crosshairs steady and parrellel as possible to the plum line, have a friend pivot the scope bubble level into the level position. Snug the level into place.
Now your scope/level relationship is congruant.

5.) now adjust your fire arm cant till you feel it is comfortable and level for "you". Use what ever method that gives you confidence in your adjustment. Use the level/level/level or what ever.

6.) while holing the rifle in this position, have your friend rotate the scope till the bubble level in the scope level indicates level. Tighten the scope rings and sight in the rifle.

At this point you have leveled your rifle to fit your eye.
And the scope is vertically true and congruant to the horizon.

This procedure works for me to shoot out to a mile and a little beyond.

If this doesnt work, you have more issues than scope/rifle cant to deal with.

Good luck guys, and dont worry to much about it! Just line it up as best as you can, and shoot. You will figure it out.

Remember, keep it fun.

 

[dthunter]

Just to add to my last post, after you have your (scope/scope level relationship) and your scope/rifle relationship aligned, you would be well advised to perform a scope function test.
This will prove if the scope adjustments are repeatable/consistant.
It will also indicate if the vertical adjustment tracks true to the crosshairs in the scope.

This is best done on a day that has nearly no wind.
Be sure to use a proven load for that rifle.
If any shots in a string are thrown, be sure to indicate this on the target, as not to use the errant shot for measurement purposes.


Get a 4 foot by 4 foot target at 100 yards.
Put a small aiming point that you can easily center your crosshairs on. Place this aiming point about 6" from the bottom edge of the target.

This will leave you with lots of adjustment room above the aiming point.

1.) shoot a three shot group, let the rifle cool for a few minutes.

2.) Adjust the scopes verticle adjustment "up" 12 MOA.
Aiming at the same target as before, shoot 3 more shots.

3.) adjust the scope up 12 MOA again, and repeat.

4.) adjust the scopes windage adjustment (right or left) 12 MOA.
Shoot 3 shots.

5.)adjust the scopes vertical adjustment "down" 12 MOA.
Shoot a 3 shot group.

6.) adjust the vertical adjustment "down" 12MOA.
Shoot a 3 shot group.

7.) adjust your windage adjustment back towards the target aiming point 12 MOA.
Shoot 3 shots.

If your scope is tracking properly, the last and first groups should overlap.
This would comfirm the scope adjustments are repeatable.

If you like, you can also measure the spans between each group (only in the planes of adjustment) and average them.
Divide the average by the number of clicks you adjusted for each 12MOA. This will give you your "ACTUAL" individual scope click value. This is GREAT information to input into a ballistics program you may use. It will be more consistant and accurate for "your scope adjustments".

After all the shooting is completed, hang a plumb line over the "first group".
if the plumb line doesnt line up all three vertical groups, your scope adjustments may not track perfectly vertical.
1/4-3/8" or less out of alignment from first group to third group doesnt concern me much.

Hopefully this is helpfull to you guys.
I am sure a few gunnutters will find a few blips and ommissions that I over looked or never adequately explained. These are both welcome and helpful.