Where does Rifle cant begin to matter?

Lobber

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Feb 22, 2016
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Is a scope level absolutely necessary? Not necessarily, but I put one on every rifle for reference. Do I use it at the range off a bench, not really. Do I use it in the mountainous terrain I hunt while setting up on side hills, shooting over sage brush, etc, etc.... Every Single Time!
 

30BR

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Feb 9, 2013
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Dave Gustin, a former NRA record holder and Palma team member always shot his rifle canted. But anytime you asked him about it his response was always, "I shoot this way because I learned to shoot this way. But DO NOT CANT YOUR RIFLE." It throws off all your windage adjustments.
He had probably close to a million rounds or more under his belt, and used to burn out barrels in a single day. yes, that's THOUSANDS of rounds in a single day. (Back when the US Government was paying him to shoot and changing his barrels.)
 

Euler

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The Attached PDF by Dr. Hazelton gives actual facts (not internet opinion). The below graphic also helps give some context regarding what matters.

Effects of Offset and cant of a rifle.jpg
 

Attachments

  • Estimation of Shot Error due to Rifle Cant.pdf
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30BR

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The Attached PDF by Dr. Hazelton gives actual facts (not internet opinion). The below graphic also helps give some context regarding what matters.
Nice! So unless you know exactly how much cant you hold, you could be off by 5" vertical at 300 yards,
Don't cant!
 

Euler

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Nice! So unless you know exactly how much cant you hold, you could be off by 5" vertical at 300 yards,
Don't cant!
That should absolutely not be the takeaway. Vertical is effected far less compared to horizontal, and you aren't going to be off by 5" vertically at 300 yards because of cant. The examples are always a 308 shooting 1,000+ yards and 5 or 10 or more degrees of cant. That is not reality. If you don't know you have 10 degrees of cant, you might want to see a neurologist.

Some food for thought: we all have levels built into our bodies, and you should be able to tell plumb to within about a 1-degree. If you cannot tell the difference, you should work on it. Also, the bubble levels are not always correct, rails are not always horizontal, tube mounted bubbles can get loose and move, etc. Something like a Sendit level would be better, but most guys aren't using those.

ear.png


IMG_0002.JPG
 

30BR

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Feb 9, 2013
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312
I dont use an angle finder on my rifles.
When they are straight, the cant error doesnt exist. Why introduce another variable that you don’t need to ?
and the 5” error is from the 300 yd chart in your attachment.

But hey, if you want to guess the cant angle, then guess the correction factor, be my guest. I’d rather just pull trigger.
 

charlesasmith

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Feb 6, 2009
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Euler: Thanks for posting the picture demonstrating differences in bubble level position of the same manufacturer's anti-cant device. I just recently discovered this issue earlier this year. Your picture clearly verifies this problem. Now I have to figure out what to do about it -Is it the base or the anti-cant device (or both)!
 

trhall

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Aug 10, 2010
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Utah
I have been watching YouTube videos on long range shooting. Primarily Barbour Creek shooting school. They did an episode where they illustrated how much a 10-15 degree cant can affect impact at 1,000 yards. What I am wondering is how much will it affect 500 yards, 400 etc? Is this a linear thing where 500 would be off half as much as 1,000? Main reason for asking is if I do not shoot beyond 600 yards, is a scope level absolutely necessary?
It is linear.
 

Euler

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I dont use an angle finder on my rifles.
and the 5” error is from the 300 yd chart in your attachment.
The chart shows -0.43-inches of vertical error at 300-yards with a 10-degree cant using a 308 (168 SMK with MV of 2700 fps, 2-inch sight height, & zero'd at 100 yards). The horizontal error is 4.95-inches.
1603987958030.png


Again, you'd have to have something serious going on to be 10-degrees off, see below for reference
1603988188681.png


@trhall , the error is non-linear. The error is dependent on time-of-flight.
 

30BR

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Feb 9, 2013
Messages
312
I stand corrected, the 5" error would have been in windage.
 

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