Canting a rifle

[Ed-WI]

If an air rifle is sighted @10 meters with no cant, what effect would say a 15 degree cant have on point of impact? Anyone know of any data? I would expect that the sight height above the bore would also effect this...

[Tony D]

Canting affects sighting in. If you are a right hand shooter and you cant to the left, your group will move to the left and low. If you have to put in a lot of windage correction, say 6 clicks or more, you might have to add in one click of elevation. How much will depend on the amount of cant and the characteristics of your rifle sight.

In practice, the shooter shouldn't have to worry about this too much. If the sights are way off, just adjust it as if you didn't cant. When you get close, you'll just find that you have to add a couple of clicks of elevation that you didn't notice before.

This is the reason why high end precision sights have a rotating base so that you can level the sight relative to your cant. The front globe can also rotate and you can even install a bubble level to make sure that you maintain the same cant angle from shot to shot.

Unfortunately, you can't use any of these in sporter class competition.

BTW, adjusting your sight is a continuous exercise while shooting. It is not unusual for the rifle to drift during a shooting session. This occurs for a variety of reasons and could include changing ambient temperature or humidity. A knowledgeable shooter watches his last couple of shots to note any drift and makes a sight correction when he sees a pattern.

[Pat McCoy]

Can't answer your question for Air Rifle, but a friend who is a math teacher told me it figures out to about 1 1/4" at 300 yards when shooting highpower. I can't hold that well, so don't worry about it, BUT do worry about making sure the cant is the same every time and remember to move both vertical and horizontal adjustment knobs when making a sight adjustment.

[Ed-WI]

Got some really good info if anyone is interested:
From Gerard:
Read the following documents on the effect of rifle cant on the point of impact :

http://home.wanadoo.nl/jhogema/skeetn/b ... ntel1e.htm
http://home.wanadoo.nl/jhogema/skeetn/b ... ntexp1.htm
http://home.wanadoo.nl/jhogema/skeetn/b ... antlos.htm

Happy reading !
Gerard

And from Daisy:
Here is a demo that shows cant angle to impact.

http://www.arld1.com/impactpointvscantangle.html

HTH
Daisy


& again, thanks to everyone for the info.
Ed

[Tony D]

Ed, good stuff. Thanks for posting it.

TD

[Ed-WI]

You are welcome.
It came from some folks on the Olympic site.
Just thought I share it here.
I think it's one of my daughters hurdles...
:-)

[jcinad]

that would be a fun math question. I suspect the velocity drop from muzzle to 10m is fairly small, so you could approximate how much elevation is dialed into a sight by using that velocity and acceleration due to gravity at 32ft/second squared.

After that a bit of trig could easily determine your new point of aim. Would love to put this question on a HS math test - bet it would confuse most and raise the blood pressure of a few.