Vertical alignment of Rifle and Scope?

[Pathfinder76]

Originally Posted by elkhunter11

No I don't. But I don't purposely introduce offset by canting my rifles either. If I found that I needed to cant my rifles for them to fit my shoulder properly, I would install an adjustable butt plate instead, just as many shotgun clays shooters do. Whether of not the shooter can detect the offset, I prefer to not purposely introduce any.

Laughing. Unbelievable.

Tell us how you know your rifle is dead level. What is your reference? How do you introduce a level to the receiver?

[elkhunter11]

Originally Posted by chuck

Laughing. Unbelievable.

Tell us how you know your rifle is dead level. What is your reference? How do you introduce a level to the receiver?

I don't use a level , I place my rifle on bags, or in my gun vice, and and judge whether the rifle is level by eye. I have used a plumb bob hung in front of the muzzle, and looked through the scope and the bore until the string is centered in both in a few instances. This is probably a lot more accurate than the tiny levels included in the scope leveling kits. If you use levels, how did you verify that the levels were accurate? Do you have a machinists level to verify them? Do you now how to adjust a machinists level?

[Pathfinder76]

Originally Posted by elkhunter11

I don't use a level , I place my rifle on bags, or in my gun vice, and and judge whether the rifle is level by eye. I have used a plumb bob hung in front of the muzzle, and looked through the scope and the bore until the string is centered in both in a few instances. This is probably a lot more accurate than the tiny levels included in the scope leveling kits. If you use levels, how did you verify that the levels were accurate? Do you have a machinists level to verify them? Do you now how to adjust a machinists level?

So you demand a level rifle and do it by eye? Thanks for absolutely making my point. I thought you needed an absolutely level rifle and scope to have a scope track correctly?

[Bowser]

As it was told to me by someone who “shot for a living”....Make sure you put a plumb line on your target. It must be plumb as well. Scope, rifle and target must all be plumb. “They” checked alignment at 25 yds. by elevation all the way up, fire a shot; elevation all the way down, fire a shot. There should be two hole on a vertical (plumb) line on your target. If not, your shot will cantor at longer ranges.

[Jerry D]

How true is this?

90 degree cant

What option is correct. 1 or 2 or neither?



Sent from my SM-A530W using Tapatalk

[elkhunter11]

Originally Posted by chuck

So you demand a level rifle and do it by eye? Thanks for absolutely making my point. I thought you needed an absolutely level rifle and scope to have a scope track correctly?

Going back to the link for the video that you posted by Tubb, did you actually listen to what he uses to level the scope? He said on the video, that he uses the lines on a garage door. Do you believe that the lines on the typical garage door are perfectly level? what kind of level does the average carpenter use when building a garage? When you hang a garage door, does it always hang perfectly level? Do garage doors ever move due to years of frost? The level on the scope can only be as accurate as the method used to calibrate it.

As for my uses, I never shoot past 500m at targets or 500 yards on animals. If my tracking was out 1/4" at 500 yards, shooting say a 3" group, I would not likely notice that 1/4" . And if I did, I wouldn't know if it was due to a very slight breeze that I can't feel or measure. And even if I did see a difference of 1/2", my scope adjustments are 1/4moa, so one click moves the point of impact 1-1/4" , so I can't even adjust for 1/2". And even if I could adjust for 1/2" at 500 yards, it would make no real difference for my uses. If I was going to shoot targets at 1000 yards, I would use the plumb bob method, as I did with a few of my target rifles, to level the rifle, and them set the crosshairs to the rifle.

[Dmay]

Originally Posted by Wrongside

This company's Reticle-Tru is some of the best money I've spent on scope mounting tools.

https://parabola-llc.com

I actually have one surplus to my needs..... BNIB....if anybody interested.
Accidentally bought two back in the day.....
And I agree, works good...

[Pathfinder76]

Originally Posted by elkhunter11

Going back to the link for the video that you posted by Tubb, did you actually listen to what he uses to level the scope? He said on the video, that he uses the lines on a garage door. Do you believe that the lines on the typical garage door are perfectly level? what kind of level does the average carpenter use when building a garage? When you hang a garage door, does it always hang perfectly level? Do garage doors ever move due to years of frost? The level on the scope can only be as accurate as the method used to calibrate it.

He is leveling the Scopes reticle to the scope level. It has nothing to do with the rifle.

[elkhunter11]

Originally Posted by chuck

He is leveling the Scopes reticle to the scope level. It has nothing to do with the rifle.

But you keep telling us that the scope must be level to track properly. You can't get the scope perfectly level , unless you use an accurate leveling method.. The lines on a garage door are hardly a precise leveling method. If I really want to be precise about leveling a scope, I will use a plumb bob, over the lines on a garage door,

[Jerry D]

I believe of the scope is not mounted directly verticle of the bore. There will be windage error in amounts that are not actually noticeable?

If the rifle is canted so that the scope is 1/16" offset to the right of the bore with a 200 yard zero (the scope is level with the induced cant)

Will the rifle shoot 1/16" to the left ar 400. At 600 it will be 1/8". 1/4" at 1000 yards. Will you notice that?





Sent from my SM-A530W using Tapatalk

[Pathfinder76]

Originally Posted by elkhunter11

But you keep telling us that the scope must be level to track properly. You can't get the scope perfectly level , unless you use an accurate leveling method.. The lines on a garage door are hardly a precise leveling method. If I really want to be precise about leveling a scope, I will use a plumb bob, over the lines on a garage door,

Tell that to David Tubb Elk. You keep talking in circles when someone spots your game. Man up and say, “Gee, was I ever wrong. Sorry”. Rather than deflecting everything like a professional con.

[elkhunter11]

Originally Posted by chuck

Tell that to David Tubb Elk. You keep talking in circles when someone spots your game. Man up and say, “Gee, was I ever wrong. Sorry”. Rather than deflecting everything like a professional con.

You posted the link, and you questioned my methods, I am simply pointing out the flaws in your link, and therefore in your argument. But I certainly do understand your frustration in having your own link turned against you, to counter your argument.

David Tubb is likely well aware of the fact that he uses methods that are not overly precise to level his scopes, but he also realizes that his methods work for him, so he doesn't let it bother him. In the same way, my methods work for me, so I don't let it bother me, if you don't agree with my methods.

But when you debate geometry, the theories are absolutes, not close enough. I am using simple geometry to point out that the horizontal offset does exist when you cant a rifle, whether you can live with that offset, is up to you.

[Pathfinder76]

Originally Posted by elkhunter11

You posted the link, and you questioned my methods, I am simply pointing out the flaws in your link, and therefore in your argument. But I certainly do understand your frustration in having your own link turned against you, to counter your argument.

David Tubb is likely well aware of the fact that he uses methods that are not overly precise to level his scopes, but he also realizes that his methods work for him, so he doesn't let it bother him.

But when you debate geometry, the theories are absolutes, not close enough. I am using simple geometry to point out that the horizontal offset does exist when you cant a rifle, whether you can live with that offset, is up to you.

Laughing. Round and around and around we go.

Again Elk, your scope must be level (geometry lesson there) but your rifle not so much. I am not wrong and no amount of wringing your hands will change that. Did you watch the second video?

[Pathfinder76]

Here is a screenshot for those who refuse to watch it.

[elkhunter11]

Originally Posted by chuck

Laughing. Round and around and around we go.

You use certain methods to set up a scope, and I use certain methods, yours works for you, and mine works for me, and Tubbs methods obviously work for him. We can't change geometry, when you cant the scope, it won't track properly, when you cant the rifle, horizontal offset must exist, those are absolutes that can't be changed. You can argue all that you want, you can post whatever links you please, but geometry is an absolute. But although we can't change geometry, we can get by using our own methods, and not be overly concerned with the geometry, if it isn't an issue for our particular application.

[Wrongside]

Originally Posted by Dmay

I actually have one surplus to my needs..... BNIB....if anybody interested.
Accidentally bought two back in the day.....
And I agree, works good...

Nice. He doesn't ship to Canada anymore, so buying your extra would be a nice easy way into one.

[Pathfinder76]

Originally Posted by elkhunter11

You use certain methods to set up a scope, and I use certain methods, yours works for you, and mine works for me, and Tubbs methods obviously work for him. We can't change geometry, when you cant the scope, it won't track properly, when you cant the rifle, horizontal offset must exist, those are absolutes that can't be changed. You can argue all that you want, you can post whatever links you please, but geometry is an absolute. But although we can't change geometry, we can get by using our own methods, and not be overly concerned with the geometry, if it isn't an issue for our particular application.

I could care less how you set up your scope.

Bottom line. Scopes that are set up level to rifles rarely actually are. It matters not. Scopes that are canted while shooting at targets at long distances will miss. Scopes that are level to targets, even when mounted on canted rifles will hit.

[AndrewM]

Have a look at the attached file and see if my math makes sense or if I made a mistake. I have an excel file to do the calculation if anyone wants that as well. These are the results I get with the math.

One degree of cant zero'd at 200 yards gives 0.07" of horizontal movement at 1000yards.
Five degrees of cant zero'd at 200 yards gives 0.35" of horizontal movement at 1000yards.

[mattthegorby]

Originally Posted by chuck

I could care less how you set up your scope.

Bottom line. Scopes that are set up level to rifles rarely actually are. It matters not. Scopes that are canted while shooting at targets at long distances will miss. Scopes that are level to targets, even when mounted on canted rifles will hit.

I am glad that I read this to the end... and now I think I get it.

While Elk's geometry still makes sense to me, it follows that the effect of the slight side-to-side cant of the bore to a plumb reticle is insignificant when compared to the error introduced by a reticle that is not held plumb due to the not compensated for cant introduced by the shooter.

At least... I think that is it?

[AndrewM]

Simple math: For a 90 degree cant angle with a crosshairs 1" from the barrel. (Side mount scope) If you zero at 200. For every 200 yards past it goes up 1". So 4" at 1000 yards.

[Salavee]

Originally Posted by mattthegorby

I am glad that I read this to the end... and now I think I get it.

While Elk's geometry still makes sense to me, it follows that the effect of the slight side-to-side cant of the bore to a plumb reticle is insignificant when compared to the error introduced by a reticle that is not held plumb due to the not compensated for cant introduced by the shooter.

At least... I think that is it?

I would call it a draw. Both methods work for what most of us do with our rifles.

Trying to describe the taste of salt with a keyboard has it's challenges.

[AndrewM]

Originally Posted by mattthegorby

I am glad that I read this to the end... and now I think I get it.

While Elk's geometry still makes sense to me, it follows that the effect of the slight side-to-side cant of the bore to a plumb reticle is insignificant when compared to the error introduced by a reticle that is not held plumb due to the not compensated for cant introduced by the shooter.

At least... I think that is it?

Yes there is horizontal movement. It is negligible though if your crosshairs are level with your target and you are zero'd to a target. Your scope would have more error than you would introduce by a cant with a level reticle.

[mattthegorby]

Originally Posted by AndrewM

Simple math: For a 90 degree cant angle with a crosshairs 1" from the barrel. If you zero at 200. For every 200 yards past it goes up 1". So 4" at 1000 yards.

That makes sense to me. The video Chuck pointed the fellow said his rifle was canted less than a degree, so if that is all it takes to compensate we are talking a pretty tiny amount. I am tempted to divide by 90... but my math skills are not advanced enough to know if it is that simple.

[mattthegorby]

Originally Posted by Salavee

Trying to describe the taste of salt with a keyboard has it's challenges.

True. Though there something about these shooting threads that is strangely addictive - like MSG.

[CNP]

Originally Posted by AndrewM

Simple math: For a 90 degree cant angle with a crosshairs 1" from the barrel. (Side mount scope) If you zero at 200. For every 200 yards past it goes up 1". So 4" at 1000 yards.

Not checking the math but I'm happy to see you've come around. 90 cants aren't typical and neither are crosshairs 1" from the centre of the bore. Shouldering someones gun with crosshairs that are not level with the rifle irritates me. I level the rifle in a bed, I then mount the scope level using a plumb bob. I shoulder the rifle...….if the image of the crosshairs is not level I will readjust my hold until the crosshairs are level. Fire away. This is "the" proper way to mount and use a scope. Mounting a scope on a canted rifle is the same as mounting a scope that is not level and will induce deviation as you have illustrated.

[Dean2]

Chuck

Chuck, OI give you credit for sticking to this discussion as long as you did. I sort of bailed a while back. Looks like you, me Cat and a couple of others have finally got through to at least the majority of the people on here. I summarized my posts for ease of reading. These pretty much clarify the issue under discussion being: If the rifle is canted but the scope is plumb to the world, no meaningful POI shift occurs. If you cant the reticle, as little as 5 degrees can cause a miss of a man size silhouette at 600 yards.

To reiterate and summarize my posts -First being Post #11 of this thread

Use a level and Plumb Bob to put a perfectly level + on a wall ten feet or more away. Mount the gun on your shoulder using sticks, bipod or offhand depending how you shoot. Level the reticle to the shoulder mounted rifle. What is important is that the reticle is level and square vertically when you are shooting it. Being square while the gun is in a vice is actually irrelevant unless you are mounting a scope strictly for shooting from a bench mounted rest like BR competition. Getting it square in a vice may not make it square when you are shooting it because your body and shoulder are not perfectly vertical or horizontally true.

Post #16

Assuming the barrel's bore is centered in the barrel and that the scope is mounted parallel to the bore then the rifle being canted has no effect on the POI changing AS LONG as the scope is square to the target and the earth. The vertical and horizontal error is induced by the effect of canting the optic when shooting, which changes the relationship of the line of sight to the bores axis, not the cant to the gun itself. A level on a gun is helpful but it must be set to the point where the scope is square to the world not the gun itself. You could literally shoot a rifle that is held 45 degrees to vertical as long as the scope is square then the vertical and horizontal shift in the POI from adjusting the scope will be accurate. For that matter, you can even hold a gun, with a scope that is mounted level to the world with the gun in the true vertical position, at a ten degree cant and you will not see any change in POI as long as every shot is always at a ten degree cant.

https://www.riflescopelevel.com/cant_tests.html

http://bulletin.accurateshooter.com/...tubb-explains/

Post #25

It is not as simple as many make it out to be. If you mount a round scope parallel to and in a dead line above a round bore, then the center of the scope and the center of the bore must by definition be in direct alignment. The issue comes in when you introduce a crosshair and an erector system for adjusting the vertical and horizontal impact of the bullet. At this point, the center of the cross hair may or many not be in the dead middle of the center of the scope. The erector system is designed to move the horizontal crosshair up and down and the vertical crosshair left and right. Any angle introduced into the alignment of the cross hair to perfectly vertical and horizontal to the world means a vertical adjustment will also create left or right adjustment to the POI and a windage adjustment will introduce vertical movement. The center of the scope and the bore has not moved, just the crosshair is moving up down or left and right.

With respect to cant affecting POI in the absence of any adjustment, this occurs due to the line of sight rotating away from direct alignment of the bore at the alignment that the rifle was sighted in at. If the crosshair was dead center in the middle of the scope, and no adjustments were being made, the cant in the crosshair would not affect the POI. Take a scope, mount it in a v-groove and center the crosshair on a dot or +. Now slowly rotate it 180 degrees, you will easily see that the crosshair moves left, right and/or up and down. This is caused by the reticle not being dead center in the middle of the scope. The further out towards the extremes of vertical or windage adjustment the more pronounced this effect is and is why scope makers recommend you use the windage screws on the mount to try and keep the reticle as close to dead centre of adjustment as possible.

[6.5 shooter]

Originally Posted by chuck

Again, the scope must be level. The rifle not so much. And, mind blowing fact here, if your scope is level and bolted to your rifle the cant (rifle cant) will be exactly the same every time.

REALLY ?? So your adding an extra margin for error into your shooting forum....go buy a bow put an old pin sight on it then same bow buy a nice level built into the sight add a peep. shoot the bow get back to me on which sight works best...rifle shooting is the same thing less variables the less chances of screwing up...hence why target shooters use fixed power scopes with AO instead of side parallax...less chance for error.

[AndrewM]

Originally Posted by mattthegorby

That makes sense to me. The video Chuck pointed the fellow said his rifle was canted less than a degree, so if that is all it takes to compensate we are talking a pretty tiny amount. I am tempted to divide by 90... but my math skills are not advanced enough to know if it is that simple.

Have a look at my earlier post. At 1000 yards it is .07”. That’s less than 0.01” per 100 yards past 200.

[Dean2]

Originally Posted by 6.5 shooter

REALLY ?? So your adding an extra margin for error into your shooting forum....go buy a bow put an old pin sight on it then same bow buy a nice level built into the sight add a peep. shoot the bow get back to me on which sight works best...rifle shooting is the same thing less variables the less chances of screwing up...hence why target shooters use fixed power scopes with AO instead of side parallax...less chance for error.

NO extra margin of error is being added into the equation. If anything, error is being removed from the equation. A plumb scope on a plumb rifle will add cant error for 98% of shooters because almost everyone naturally cants a rifle when shouldered. Removing that error, and adding a scope level will always give you the most error free mounting of a rifle designed to be hunted and thus shoulder fired.

[6.5 shooter]

Originally Posted by chuck

Well lookie here. Huh.

https://youtu.be/eCoHG23TQcY

Set target at set range.. crank them turrets up or down video would be totally different.

If you can hold your rifle totally level 100% of the time at all ranges then your theory works but we NEVER hold our rifles the same every time and cant in the scope just adds one more variable.