Scope Cant

[MarkTX]

I fitted a scope, but I am unsure how to tell if it is canted to the left or right in the rings. I know there are levels to attach to scope rings, but those seem like they will only be helpful if the rifle itself is perfectly positioned vertically. Is there a trick or tip anyone can share with me?

[Matchstickshooter]

A little trick I've tried that may or may not work for you......
 I hang a string with a weight at the end, and shoulder my rifle. I line the vertical lines of the scope up with the string.
 So every time I throw the rifle up to my shoulder I'm somewhere near...

[39M]

I'd shoot it.

If it's grouping good, and the scope is canted, you'll notice that the POI may shift from left to right, or right to left, as you shoot at different distances.

If it's not grouping good it probably doesn't matter.

[SagaciousKJB]

A little trick I've tried that may or may not work for you......
 I hang a string with a weight at the end, and shoulder my rifle. I line the vertical lines of the scope up with the string.
 So every time I throw the rifle up to my shoulder I'm somewhere near...

I like doing it this way too, that way it's square with how I hold it.  I once went out of the way to get a bipod on an old .22LR and had it all level, then come to find when I held it the most comfortable way, the scope cross-hairs were tilted.  Had to hold it awkward to get the horizontal line to be parallel with the ground--which is really what's most important.

In my opinion it doesn't really matter much unless you're trying to shoot very teeny tiny  match-size groups, or very long ranges (100+ yards) where a minute of angle really counts for something.  Inside 50 yards, your scope would have to be very grossly canted for you to really notice, unless you're trying to shoot dimes using Mil-Dots or the edge of your duplex reticle.

[BenjiHunter]

Put one level on top of the picatinny rail, to get the rifle level.
And another level on top of the scope, if the elevation knob is flat.
When both are the same , you're good.

[uglymike]

A little trick I've tried that may or may not work for you......
 I hang a string with a weight at the end, and shoulder my rifle. I line the vertical lines of the scope up with the string.
 So every time I throw the rifle up to my shoulder I'm somewhere near...

I do the same thing, use a brick, then wait 'till it stops swinging. I have the rifle in a leveled Caldwell lead sled and move the elevation until it lines up exactly with the string. This is probably the wrong way, but it works for me.

[MarkTX]

Thanks, these are all good ideas. Intuitively, I thought of 39M's idea, or something like it, but I was not sure about the physics of it at all. And like another said, good to know eyeballing it won't matter much, unless distance is 50 yds or more. I find myself with too much time on my hands, and this whole twisting the scope barrel in the rings exercise made me feel frustrated and OCD.

[39M]

Every once in a while I get it just right on the first try. Eyeballing it.

Most of the time I'll have to adjust a time or two while shooting when I notice that it's canted a little just by looking.

To start with, I usually just line up the vertical on a door frame inside the house or a fence picket if outside.

I guess I'm just too lazy to be messing with strings and mirrors.

[rsterne]

Consider this drawing.... A is the wrong way to install a scope, B is correct, and then you need to hold the rifle as in C....



When installing the scope, the vertical crosshair must line up with the bore, as in B.... I use a mirror at half the minimum focus distance of the scope, and view the reflection of the objective and barrel in the mirror.... Rotate the scope in the rings until the crosshair bisects both.... When shooting, hold the crosshairs vertical/horizontal, as in C, and don't worry if the rifle is canted slightly.... The bullet follows a vertical path in the absence of wind.... That path must align with the vertical crosshair in the scope....

Bob

[39M]

Of course if it's a breakbarrel, you may just be spittin in the wind....

[MarkTX]

Bob, I knew you would have an answer, but this blows my mind. I suspected as much. Why can't everything be 90 degrees. Easy peasy.

[SagaciousKJB]

Consider this drawing.... A is the wrong way to install a scope, B is correct, and then you need to hold the rifle as in C....



When installing the scope, the vertical crosshair must line up with the bore, as in B.... I use a mirror at half the minimum focus distance of the scope, and view the reflection of the objective and barrel in the mirror.... Rotate the scope in the rings until the crosshair bisects both.... When shooting, hold the crosshairs vertical/horizontal, as in C, and don't worry if the rifle is canted slightly.... The bullet follows a vertical path in the absence of wind.... That path must align with the vertical crosshair in the scope....

Bob

So does that mean if the scope's minimum focus is 7 yards, and has an AO, you should turn the AO down to 7 yards and view from 3.5 yards?

[nervoustrigger]

That is correct.

[Hoosier Daddy]

Isn't the scope rail usually centered with the bore of the barrel? I can't think of a normal situation it wouldn't be if mounted to the breech/ receiver/ barrel.

[nervoustrigger]

In a perfect world, yes.  In practice, there are several sources that can and often do lead to misalignment...receiver drilled slightly off (or pivot slightly off in the case of a springer), dovetail machined slightly off, scope rings biased slightly, or barrel bent.

[39M]

Isn't the scope rail usually centered with the bore of the barrel? I can't think of a normal situation it wouldn't be if mounted to the breech/ receiver/ barrel.

They are suppose to be.

[Nvreloader]

Here is what I use, to make sure that the vertical cross hair is square and true,
it sure tighten my groups up @ 300yds and beyond for my CF pistols/rifles.

You have to adapt the ranges to fit your AR and use,
Can also be used to check the clicks amounts, if you are a dialer. 



Tia,
Don

[SagaciousKJB]

What's it mean when you look in the mirror and the verticle cross-hair is parallel with the scope objective and barrel, but it's not in line with the bore unless you tilt your head a little?  Is cant or my head not being in the right spot?

[avator]

If I'm correct.. cant is exaggerated with higher mounts. I mount my scopes with the lowest rings possible. Even if it means removing the rear/front sights.

[rsterne]

If the vertical crosshair is not bisecting the image in the mirror of both the objective and the bore, you need to rotate the scope in the rings until it does....

Bob