Canting the rifle

[Dangerous_dave308]

I was wondering if there was any information on the effects of canting ones rifle. I was hoping to find a way of calculating the shot error when canting the rifle. I understand that the height of the scope above the bore as well as the range, balistic pate etc. must be factored in. I recently had trouble getting a tight group with a recently scoped rifle. My friend swears that it was due to mt canting the rifle. I would love to be able to put a real number on that effect.

[woods]

Cant Errors - Long range shooting

solution

use an EXD

BROWNELLS : EXD ENGINEERING : EXD ENGINEERING VERTICAL RETICLE INSTRUMENT - World's Largest Supplier of Firearm Accessories, Gun Parts and Gunsmithing Tools

while rifle is in a vise



aim out the window or door to a distant horizontal or vertical object (weight on a rope, 4' level on a fence, vertical corner of building) and level reticle.

Install a ScopLevel

Scoplevel Anti Cant Leveling Device



so you can duplicate holding the rifle uncanted in the field or on the bench.

It is not as important that you hold your rifle uncanted as it is that you hold your scope reticle level.

[Michael Eichele]

A simple formula is the sine of the degree of cant * drop at desired range from boreline. Drop from boreline is NOT corrected for your zero.

An example would be a drop of 273" at 877 yards.

The sine of the degree 1 = .02

Take .02 * 273" and you have 5.46". This is how much horizontal displacement you will have at 877 yards with a 1 degree cant.

[gahlizard]

i hope i can remember the "easy" formula i read about a few years back...i believe you multiply your inches of drop and degrees of cant and then divide that by 47, it should quantify things for you for the first ten degrees of cant, give or take a little. the resulting number should be the approx number of inches that you will be low and right or low and left. i think that was the formula i read of. hope it helps. greg

[MontanaRifleman]

Hmmmm... IMO you should not be compensating for canting your rifle, because you should not be canting your rifle. Get an anti-cant bubble level.

-MR

[Dangerous_dave308]

Originally Posted by gahlizard

i hope i can remember the "easy" formula i read about a few years back...i believe you multiply your inches of drop and degrees of cant and then divide that by 47, it should quantify things for you for the first ten degrees of cant, give or take a little. the resulting number should be the approx number of inches that you will be low and right or low and left. i think that was the formula i read of. hope it helps. greg

Thanks alot. Together with the help from this site and some just plain thinking I now have a handle on my problem.

[edward hogan]

Originally Posted by woods

Cant Errors - Long range shooting


It is not as important that you hold your rifle uncanted as it is that you hold your scope reticle level.

Agree!

If you mount your scope using a boresighter with collimating grid (Bushnell 74-3333) you will notice any cant in your aiming. Keep the horizontal reticle element level across your target and you won't cant your rifle.

ETA: If you are shooting from benchrest position, use a square as your aiming point. Place reticle so it's in-line with bottom corner of your aiming point, and shoot your groups there. Easy to see when your crosshair is right on the corner of a 90 deg angle. Hold that same precise point for every shot and watch your groups improve.