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Post by ozark on Jan 16, 2009 17:36:46 GMT -5
Ordinarily I would just type a lesson describing canting a rifle and the effects it has on accuracy. Here I am asking how you shooters avoids this shooting error and how you mount scopes to insure that they are directly over the bore and correct with regards to the vertical and horizonal? I will state a fact here in hopes of getting some minds focusing on the subject. Fact: If a rifle is zeroed while perfectly vertical with the scope center 1 and 1/2 inches above the bore so the bullet impacts on the crosshairs at 100 yards. If the scope is canted 45 degrees the bullet will miss the crosshair centers by about 3/4 inch. at 100 yds. double that at 200 and etc. Ok, jump on this one. Ozark
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Post by jims on Jan 16, 2009 19:04:21 GMT -5
I use a device made by Segway Industries called a Reticle Leveler. Some use a plumb bob on a string I have been told.
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Post by ozark on Jan 16, 2009 19:20:29 GMT -5
Jims, that is good for mounting. How do you insure you are not canting the rifle while shooting in a hunting situation?
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Post by jims on Jan 16, 2009 19:34:06 GMT -5
Sorry about that. I really do not have anything available that I use other than looking. I did buy from Sinclairs or Brownells an attachable level bubble device that you can look at before shooting to make sure everything is level but it always seemed like such a hassle I never used it. It did not cost much as I recall. It attached to the scope on or near the turrets as I recall. I may have it in the gunsafe and will try to locate it.
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Post by ozark on Jan 16, 2009 19:43:42 GMT -5
I use the verticle as a guide while shooting at game. Shooting on a side hill slope there is a tendency to misjudge the horizonal. It is an optical illusion for me on slopes. A good practice is to hang a plumbbob or weight on a string and practice getting the vertical line on the string or parrallal to it. Canting can throw you off a bunch at longer ranges. Hope others give us some pointers.
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Post by youp50 on Jan 16, 2009 21:40:49 GMT -5
I do it by eyeball. I get paid to install piping systems. As a whole my trade develops a good eye for plumb and level. We do have legends. They go like this "Don't let Stuey look it in, he has a bad eye."
I got a good eye, Ben.
You are correct about the background lines. They can create an optical illusion. An example being a rain leader (downspout) in a parking garage. If the general contractor had a problem in a corner and it is not plumb, you better follow his lines. If you don't the pipe will always appear out of plumb, the building can't be crooked. Any straight building makes a good background. I use a corner in my basement for background.
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Post by whyohe on Jan 16, 2009 21:40:56 GMT -5
i cant give a real good one but my rifle has rectangular lugs on the sides and i look at that and see if it looks level and the flats of the stock at the recever. its not perfect but in hunting situations it gets me close. also if your recever or scope mounts are flat id use that too.
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Post by chickenhunter on Jan 17, 2009 2:16:36 GMT -5
I lap the rings to ensure the rings are in line with each other. Then level the receiver. Then level the scope from the top turret with the cap off.
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Post by mike.dawson on Jan 17, 2009 8:31:07 GMT -5
How much would you have to cant it to miss the 8" kill zone on a whitetail? ;D Mike
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Post by raf on Jan 17, 2009 8:31:54 GMT -5
I used to, and probably still do, cant my bow when shooting from my elevated blind at deer which caused me to shoot right. I went out and bought a little bubble level to attach to the bow. When a deer appears and I'm drawing the bow and aiming I never look at it. Either don't think of it or there isn't time. So I don't put anything on my rifle. I don't think I cant my rifle although if some one were to measure somehow I like almost everyone else likely do a little. At the range I have my rifle on a rest and a great deal of care is taken before each shot to make sure the front rest in properly positioned and the crosshairs are vertical.
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Post by ozark on Jan 17, 2009 12:18:44 GMT -5
How much would you have to cant it to miss the 8" kill zone on a whitetail? ;D Mike It depends on the range but at ordinary distances canting would not cause a miss. But here where shooters are attempting to get the most accuracy possible it will cause groups to spread. Correcting it doesn't cost money. Ignoring its effect isn't something the dedicated shooter will do.
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Post by deadeye on Jan 17, 2009 15:48:15 GMT -5
my competition rifle has a level built into it. on rifles while playing at very long distance's i simply lay a level( rectangle>approx-2'' long w/1/2" sides) i bought at hardware store on top of scope caps which are flat,can use two sided tape if a person wishes . i have found that after shooting very long ranges-1,000yds plus often,you eventually subconsciously get very close without the level but once in while i just pull that cheap hardware level out of my pocket to just check my bubble ;D ;D ;D
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Post by edge on Jan 18, 2009 20:23:30 GMT -5
In the East it is normally easy to get plumb, but out West, especially in a valley I don't think that you can count on your mind to keep you level.
Long range guys use a bubble on their scope. You need to remember that airplanes have gyroscopes to ensure pilots fly level. Flying in clouds it is not too uncommon to end up flying upside down without an artificial horizon!
edge.
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Post by raf on Jan 18, 2009 21:43:19 GMT -5
Flying in clouds it is not too uncommon to end up flying upside down without an artificial horizon! edge. I can confirm that. 42 years ago I got a private pilots licence and it was demonstrated to me by my instrutor. We climbed up into a cloud and he covered the instruments with his clip board. You got the sensation of changing direction and you corrected. You couldn't feel what was happening until we came out the bottom of the cloud, unexpectedly, and could see the ground and the horizon. His only statement then was "that's why you don't fly through clouds".
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Post by deadeye on Jan 19, 2009 11:02:42 GMT -5
springfield armory went out of business in the scope business but they did offer a great option to help prevent canting on their government models -a built in level @ internal bottom of sight post. i have talked with technical people for scope companies about incorporating this in,their response-we cant figure out how to squeeze it in their-too bad
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Post by petev on Jan 21, 2009 10:25:51 GMT -5
Fact: If a rifle is zeroed while perfectly vertical with the scope center 1 and 1/2 inches above the bore so the bullet impacts on the crosshairs at 100 yards. If the scope is canted 45 degrees the bullet will miss the crosshair centers by about 3/4 inch. at 100 yds. double that at 200 and etc. Ok, jump on this one. Ozark I had no idea what difference canting would make, so I am careful to not do it. I use the verticle crosshair and trees as a general guide, but I know my rifles well enough, and am conscious of keeping it plumb, that I dont do it. I had assumed that it would make a lot more difference than reported above, but I think I will continue to be watchful of it anyway, just to be on the safe side. I, personally think that it is much more easy to cant a shotgun when swinging on birds, and since I started being careful about that starting a couple of years ago, I seem to have been hitting more of them. Pete
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Post by ozark on Jan 21, 2009 10:48:53 GMT -5
Since the shotgun bead is so near the center of the barrel canting should not be as critical. I have tried to think of this subject taken to the extreme of canting a scoped rifle 90 degrees. At that point windage would in effect become elevation and visa versa. At 90 degrees the bullet would never intersect with the crosshairs. In fact would never get within 1 1/2" provided the scope was that distance above the center of the bore. Canting is just one of many things that can cause inaccuarcy. I think pete has the best answer in that he is trying to eliminate canting as much as he can. Ozark
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Post by edge on Jan 21, 2009 11:48:01 GMT -5
Let's remember that canting the rifle reduces the effective scope height.
Let's look at ozark's 90 degree example.
A 250 SST @ 2300 fps 1 3/4 scope height zeroed at 180 yards.
If you turn the rifle 90 degrees and fire at a target 180 yards away, the bullet will hit LOW 13 inches and about 12 inches in the direction of the scope ( left/right). You will miss your POA by almost 18 inches.
Let's take a more reasonable cant, say 10 degrees and try for a 300 yard shot.
Elevation will only change by about 0.02 but your windage will be off by about 3 1/2 inches with a perfect hold.
edge.
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Post by ozark on Jan 21, 2009 12:42:13 GMT -5
The bottom line is that canting can cause a little or a lot of inaccuracy. Avoiding it can increase accuracy. Here, where squeezing the very last ounce of accuracy out of rifles and loads avoiding canting the rifle is one more factor to correct. Ozark.
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Post by chuck41 on Jan 27, 2009 11:00:40 GMT -5
Same here. Only takes a little tweaking to get it right if you concentrate on what you are doing and have a decent background.
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