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Scope cant and a different horse.

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/26/2008 at 13:14
8shots View Drop Down
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Today I again shot with a canted scope,
 
Shot 1> Zero shot
Shot 2> Scope and rifle canted
Shot 3> Scope canted Rifle level.
Shot 4> Scope canted about 15 Deg Dialed up 24 Clicks.
Shot 5> Scope dialed down 6 clicks canted 15 Deg.
Shot 6 > Scope kept level, rifle canted.
Shot 7 > Scope canted about 40 deg right.
Shot 8 > Scope canted about 40 deg and elevated a further 10 clicks.
Shot 9> Scope canted same 40 deg and dialed down 44 clicks.
Shot 10 > Scope held horizontal, rifle canted.
 
Summation of test. The bullet follows the reticule cant, regardless of the rifle cant. In other words if the rifle is kept level, and the scope is turned 10 deg, the bullet will impact 10 deg right or left. If the scope is turned in increments of 10 deg at a time, it will shoot a 180 deg arc above the horizontal line if the elevation was dialed up. If the elevation was dialed down, it will do the same arc below the line.
If the rifle is canted to compensate for a canted scope,and the scope is kept level, the bullet will continue to impact straight up or down as if the scope and rifle was set up with both being level.
A small cant hardly shifts the impact left or right of the vertical. See bullets 4 5 and 6.
If the reticule is not altered after zero, the rifle or scope can be canted left or right and the bullet still impacts on the same point. 
 
At 100yds you really need to screw things up badly for a canted reticule to effect your shooting, even if you are dialling in elevation. see shot 4. Dialled lots up on a 10 deg cant, which was very visible as a cant.
So setting up a scope by eye, checking if it looks level, is good to go.
No ways would the other guys system work of shooting to check for scope cant, unless you want to see a 20 deg off cant or you dial in a 4 foot elevation.
 
And please, each one that reads this post send $1 so that I can buy new scope grub screws.
 
 
 
,


Edited by 8shots - April/26/2008 at 13:19
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/26/2008 at 14:52
sakomato View Drop Down
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Hey 8shots, my dollar is on the way.  Wink
 
Well what started me out on this stuff was wondering whether the scope was rotated or the rifle canted when my POI was progressively off to the right.  I do a lot of shooting and did not notice if the rifle was held off level and did not notice if the reticle was off horizontal.
 
Since then I have gotten the anti cant bubble and the level-level-level and those 2 things seem to have straightened things out.
 
I agree with your findings and shots 7, 8 and 9 are what I'm aiming to avoid.  I think it is possible to cant your scope 10 to 15 degrees when in an awkward shooting position and that would have a significant effect on your POI at 300 yards and beyond.  15 degrees is 5 minutes on the clock face and might go unnoticed.
 
I do think that with a real benchrest tack-driver rifle that will shoot in the 3's and 4's that you could set your reticle to be perpendicular by cranking up and seeing if it hit on the vertical axis (if you held your rifle to the same cant everytime).  That is what the guy writing that article was talking about.  But I think that with all your hard work and my brain power Loco analyzing this we have gone much further than his article took us.  Big%20Grin
 
The horse's teeth have now been counted.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/26/2008 at 17:57
Dale Clifford View Drop Down
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a good way to avoid canting problems is to use a bdc which is close to the distance you are using then dial in the rest, which may be something between 4 and 16 clicks. this is the method recommended by NF
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/26/2008 at 18:56
mercenary1947 View Drop Down
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 Uh Huh .... can't believe you went to all that trouble ! Summation .... zero cant in any respect or problems . So since she was that high at 100 yds . what range is it sighted in for ? Was thinking of installing my new scope on my 30-06 instead of my 308 and the trajectory of the bullets are a lot flatter on a 308 . It's been pouring rain here on and off for days and can't get to the range anyway . . If that block in the middle is an inch high ??? it's landing the lead about 6 " high ? Of course I just noticed shot 3 is dead on closer than 1 & 2 ... with the scope canted it seems more acurate ? Depending on what new scope rings and mounts will cost me now .... I may be able to send that dollar ---  Down%20the%20Toilet or am I just lost ??  Gas = $3.70 gal. today .... diesel = $ 4..60   may have to ride a bike next year to the mountains .
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/27/2008 at 09:15
8shots View Drop Down
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The high shots are just dialed up in order to try and show the effect of scope can't. In other words increasing the size of the arc. The rifle was zeroed, and from there just dialed up, and not zeroed for any particular range.
Further, do not look at the accuracy as an absolute, look at the trend. It moves this way or that way etc. Shooting with a canted scope or rifle is rather difficult. Shooting accurately with everything level and square is also difficult! So make some allowances as the idea was to show the basic principles, rather then the absolute.
 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/27/2008 at 09:25
8shots View Drop Down
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Sakomato, should your rifle be zeroed at say 100 yds and you use kentucky windage, a canted reticule will not effect your vertical line. My rifle was zeroed at 100 yds with a canted reticule. That means I hit the black suare at 100 yds, canted reticule and all. Now, if I want to allow for say a 6 inch drop, I simply aim 6 inches higher. My bullet, irrespective of a canted rifle or scope or both, will still go six inches high vertically above the zeroed point and gravity will bring the bullet back to the zero point 300 yds out.
Should you however not use Kentucky windage and your reticule is canted, and you now dial in say 12 clicks, the bullet will pass say 4 inhes right and arc down to miss your zero point to the right. See my shot 7 and 8.
So as long as you do not touch your dials and you aim in a straight line above your target a canted reticule does not matter. Look at it this way, say your reticule dissappears totally and you only have a dot where the vertical and horizontal meets. As long as that dot is not moved you will hit the zeroed point at the distance it is zeroed for, irrespective how you hold the rifle or scope. Should you wish to hit something further, you just aim the dot a little higher, directly above your desired point of impact.


Edited by 8shots - April/27/2008 at 09:30
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/27/2008 at 11:55
sakomato View Drop Down
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Originally posted by 8shots 8shots wrote:

So as long as you do not touch your dials and you aim in a straight line above your target a canted reticule does not matter. Look at it this way, say your reticule dissappears totally and you only have a dot where the vertical and horizontal meets. As long as that dot is not moved you will hit the zeroed point at the distance it is zeroed for, irrespective how you hold the rifle or scope. Should you wish to hit something further, you just aim the dot a little higher, directly above your desired point of impact.
  
 
Okay, so what happens if you are holding the horizontal reticle canted, then the verticle reticle is off perpendicular.  Then if you hold above the target you are going to naturally keep the verticle reticle through the target.  That would mean that the POI would be to the right or left.
 
IOW, if you were shooting at a target 500 yards away with a rifle zeroed at 100 yards that dropped 48" at 500 yards.  You would hold the crosshairs 48" above the target (or what you guesstimate is 48" at 500 yds) and would line up the target on the vertical reticle.  The vertical reticle being canted would cause your POI to be off.
 
So, IMO, canting the reticle will move POI with plain hold over, ballistic reticles and cranking elevation turrets.
 
What do you think?
 
I don't know if this has been referenced before but here's some more reading that I found http://www.riflescopelevel.com/cant_errors.html


Edited by sakomato - April/27/2008 at 12:33
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/28/2008 at 04:28
8shots View Drop Down
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Sakomato, you are correct that if your reticule is canted and you aim above the target, with the bottom of slanted reticule going through the target, you will miss it to the left or right depending on the direction of your can't.
My point was that if you simply aim vertically above the target, and never mind where the bottom of the reticule is pointing, you will hit your target dead on if you allowed the correct amount. In other words if I aim directly above the target, the vertical would not naturally be through the target. I would have to aim above and to the side in order for my vertical reticule to go through the target.
 
In other words I would have to aim at my shots 7 or 8, which is not directly above the target, but above and right.
 
The link you posted is excellent, specially the 3D drawing. The article supports everything we have said. If you read my earlier post, I have allways maintained that gravity plays a role on a canted rifle. And for that you need distance. 100 yds will not show the effect of gravity on high powered rifles.
Also note, the rifle has to be canted, not the scope, when the shot is made in order to observe the effect of gravity. So if you have a canted scope and the rifle is zeroed to 800yds, and you hold the rifle level with the scope canted, you will hit your target, all other things being equal. keep the scope level, which means canting the rifle, gravity will force the bullet off of its normal arc.
On short distances, and I am guessing, say 200 yds, gravity will not have this effect, and you can cant the rifle or scope, as long as it was zeroed for that distance, and still have a high level of accuracy.


Edited by 8shots - April/28/2008 at 04:48
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/28/2008 at 07:38
cyborg View Drop Down
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8 thanks brother, you sure spend alot of time doing things for the rest of us. Nice to have you around brother.
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