Is this the same as canting?

[cdoc42]

I have a Caldwell Stinger Shooting rest that I used to position a rifle scope reticle. Making sure the rifle was empty and the bolt was removed, I set up on the kitchen island countertop and used a neighbor's fireplace chimney as a vertical guide, being fairly certain it was level, and got my verticle reticle level. For the heck of it, I put a carpenter level on the rifle rest and found there was a 0.58" difference in the height of the right vs the left legs. I positioned the reticle on the chimney again, then slowly increased the height of the right leg with shims. Checking the reticle again I found it stayed vertically level but the point of impact shifted to the left.

Is that the same as canting?

I never paid much attention to the rifle rest all these years as long as my view through the scope looked level. I never canted the view on purpose to see what might happen. I did experience a situation where I set my reticle up and a friend who happened to look through the scope told me it was not verticle. When I looked through, it sure looked verticle to me. Apparently, we were holding the rifle in two different positions of comfort.

How much will the point of impact change between the two of us if we both shoot that rifle?

 

[Ifishsum]

Canting is the crosshairs not staying level on the target (or not level with the rifle to start with)

POI itself won't necessarily change a lot if you both shoot the same rifle at 200 yds or less, but if one shoots canted it will track a bit diagonally as distances increase. Vertical adjustments to the scope for longer ranges will also push the impact sideways to some degree, depending on how much cant of course.

 

[JohnKSa]

The rifle bore needs to be angled upwards to create a trajectory that will put the bullet on target.

Gravity starts pulling the bullet downward as soon as it leaves the bore. If the bore isn't aimed upwards, the bullet will never go higher than the bore and can't even hit anything that's level with the bore.

But the angle needs to be STRAIGHT upwards so that it is in EXACTLY the opposite direction as gravity. The upward angle of the bore is to counteract gravity so it has to be in exactly the opposite direction of gravity.

So let's say we have the rifle set up perfectly for 100 yards. The bore, relative to the sight line is angled up perfectly so that at 100 yards, the bullet will hit the bullseye.

Now let's cant the rifle slightly to the right. Now, instead of the bore being angled upwards to perfectly counteract gravity, it's angled up and to the right. Not as much of an upwards angle as before (so gravity won't be perfectly countered) and now there's some deflection to the right which will make the bullet go right.

With the slight cant to the right, the bullet will hit to the right and a little low on the target at 100 yards. Unless the cant is really a lot, the movement to the side will be much more noticeable than the lower impact.

The more the rifle is canted, the more the bullet will move in the direction of the cant and the lower the bullet will hit on target. The farther the target is downrange, the more significant both errors will be.

Which means:

1. When a rifle is being sighted in, the scope crosshairs should be perfectly horizontal and vertical with the rifle held in the normal shooting position.

2. When shooting, it's important to hold the rifle the same way every time.

3. If a shooter has trouble holding the rifle consistently or being able to tell if it's being held level, it may be worthwhile to look into one of the solutions out there to help insure that things are level/consistent.

 

[cdoc42]

JohnKsa, is there any need to consider the level of the table on which your equipment stands, and/or the level of your rifle rest as well?

Now, I suspect, if it does matter from a perfectionistic sense when in the field or even in your hunting hut, all bets are off with respect to the level of everything upon which you rest your rifle. No?

 

[JohnKSa]

If the rifle is level (and it was level when it was sighted in) then you should be fine in terms of cant.

From a practical perspective, if you are using the table as a frame of reference to level the rifle during sight in and the table isn't level and then you shoot under different conditions, that could be an issue. That would be because you sighted in with a cant (because you were referencing the slanted table and not actual level) and then shot with the rifle level.

The issue is that the rifle needs to be shot the way it was sighted in. If it was canted when sighted in, the cant needs to be the same when shot. Of course, it would be really hard to get a cant angle the same every time. The better option is to make sure you keep the rifle level during sight in and also when shooting--people are generally better at being able to tell if something is level than they are at getting an angle off of level correct.

 

[44 AMP]

The issue is that the rifle needs to be shot the way it was sighted in.

OR, turn it around and say the rifle needs to be sighted in the way it will be shot.

Doesn't matter if the rifle is on a rest measured to three decimal places to be dead level or if it being held in your arms unsupported and canted (tipped) a degree or three, as long as it is sighted in the way it is shot, you're as "on target" as you can physically be.

Its when sighted in one way and shot another that the difference matters.

 

[Shadow9mm]

Canting is when the rifle is rolled to the side. This causes the scope not to be directly above the bore.

I use the real avid scope leveling system. Works like a charm. It indexes on the barrel and scope bell to make sure they are straight above each other then shines a light through the scope so you can level the reticle itself against a board with lines on it.

Super quick and easy, love it.
https://a.co/d/cvCE1t5

https://youtu.be/7eEo9ZOcckA?feature=shared

 

[44 AMP]

This causes the scope not to be directly above the bore.

And the scope not being directly above the bore is a problem, how??

 

[jmr40]

We're talking about 2 separate things, but both may be happening at the same time. Sometimes the scope is mounted canted. If the shooter mounts the rifle so the crosshairs are perfectly vertical, then the rifle is canted. As long as it isn't significantly off it won't cause a problem at close or even moderate ranges.

But as range increases the bullets will start impacting either right or left of point of aim. The scope can be mounted perfectly, and the shooter can still cant the rifle.

When hanging targets at the range it is best to try to get the targets hung as close to vertical as possible. If the target is canted, then the shooter will often adjust the rifle so that the crosshairs are vertical in relation to the target. If the target isn't hung straight, then you are canting the rifle.

 

[Shadow9mm]

And the scope not being directly above the bore is a problem, how??

Is this a test? If you had the rifle and scope level but offset the scope 1in to the left how do you zero the gun? Do you zero it so the optic is parralel with the bore and know that your rounds will always impact 1in right of point of aim? Even worse would be a point of aim point of impact zero. Say at 100yds. If you shot closer you would hit right of point of aim, if you shot further away your impacts would start shifting further and further left.

Cant ofsetts the scope in relation to the bore although not to the degree of my illustration, but with the same results. Leveling the gun, generally off the receiver, and the scope together, as it typically done, alligns them on the vertical axis centering the scope over the bore. And many shooters also add a level to the gun or optic to reference when at the range to prevent cant and the problems it creates.

Cant/offset, forces you to zero and have holds for 2 different axises. It is also generally of an unknown ammount and inconsistent making things even harder. If thats not a problem i dont know what is.

 

[44 AMP]

Is this a test? If you had the rifle and scope level but offset the scope 1in to the left how do you zero the gun?

I suppose in a way, its a test. How do you zero the gun?? The same way generations of people with side mounted scopes did, and still do.

Remember that no matter where you mount the scope it is only going to be perfectly zeroed for one load at one range. Everything else is going to be "off" to some degree and adjusting to compensate for that is part of marksmanship.

Certainly, mounting the scope directly over the bore (and as low as practical) is the preferred method, because it is superior and simpler when compensation is needed, but it is not the only way things can work.

Consider, for just a couple of examples, the M1C /M1D sniper rifles, and numerous Winchester 94s with side mounted scopes. Lots of game has been taken and enemy soldiers killed over the years with rifles using side mount scope system. It can be zeroed, and certainly does work.

Yes it does have some limitations compared to direct over the bore mounting, but there's no free lunch.

Do you zero it so the optic is parralel with the bore and know that your rounds will always impact 1in right of point of aim?

If your rounds are impacting to the right (or any direction) from your point of aim, your rifle is not "zeroed". "Zero" literally means that at a given distance, your line of sight and the line of the bore meet with "zero" difference between POI and POA.

While "zero" is nearly infinately adjustable, it is only "on" at one distance at t a time, and all other distances must be compensated for, either by aiming "off" or by readjusting the sight system for the new "zero" position.

The direct over the bore mounting system is the best for that, but it's not the only system that works acceptably well.

 

[Shadow9mm]

I suppose in a way, its a test. How do you zero the gun?? The same way generations of people with side mounted scopes did, and still do.

Remember that no matter where you mount the scope it is only going to be perfectly zeroed for one load at one range. Everything else is going to be "off" to some degree and adjusting to compensate for that is part of marksmanship.

Certainly, mounting the scope directly over the bore (and as low as practical) is the preferred method, because it is superior and simpler when compensation is needed, but it is not the only way things can work.

Consider, for just a couple of examples, the M1C /M1D sniper rifles, and numerous Winchester 94s with side mounted scopes. Lots of game has been taken and enemy soldiers killed over the years with rifles using side mount scope system. It can be zeroed, and certainly does work.

Yes it does have some limitations compared to direct over the bore mounting, but there's no free lunch.



If your rounds are impacting to the right (or any direction) from your point of aim, your rifle is not "zeroed". "Zero" literally means that at a given distance, your line of sight and the line of the bore meet with "zero" difference between POI and POA.

While "zero" is nearly infinately adjustable, it is only "on" at one distance at t a time, and all other distances must be compensated for, either by aiming "off" or by readjusting the sight system for the new "zero" position.

The direct over the bore mounting system is the best for that, but it's not the only system that works acceptably well.

I never said it was the only way to do it, but it is the best way to do it currently. cant/offset does cause a problem, problems can be compensated for but preventing them is better.

Yes you are only zeroed for 1 distance, (presuming you don't have a calibrated bdc reticle with multiple aiming points). But adding in horizontal offset, in addition to vertical offset, trajectory, wind, and other factors, seems foolish and problematic, especially if it can be easily avoided.

And I still posit that, if a scope were intentionally offset like "the M1C /M1D sniper rifles, and numerous Winchester 94s " aligning the optic to be parallel with the bore and simply having the bullet hit 1/2in right or so, would be preferable as it reduces the need to calculate for the horizontal offset. you simply have a target with a point if aim for the retical, and a point of impact for the bullet. much like precision shooters use so they don't degrade their point of aim. The on in this article for example with the excellent explination of how to use it. simply calibrate it for your offset and rotate it 90 degrees.
https://bulletin.accurateshooter.com/2019/03/five-free-printable-precision-shooting-targets/

 

[Jim Watson]

I have seen pictures of a top target shooter with a considerable cant in offhand. He is in a stable stance and makes the gun fit him. I bet he recorded the W&E sight settings for all usual ranges.

A slightly related subject, we read of Bwana's double express rifle being "regulated" to converge at a particular range. Not much of a problem on a hunting rifle, if the barrels are an inch apart and regulated for 100 yards, then the hits will be an inch apart the other way at 200. Which is pretty far for an iron sighted big game gun. However, there are some out there regulated to shoot parallel. Ray Orodorica wrote that his double's individual barrel groups were centered at the barrel spacing as far as he could resolve the target.

 

[44 AMP]

Double rifles in "express" cartridges are made to be short range stoppers. Guns intended to stop very large angry animals before they reach contact distance. Often hunted in thick cover where range is short. Special tool for a special task. Pretty good one, in skilled hands, too!

When Bwana wants to take a 200yd shot, he uses a different rifle.

 

[JohnKSa]

I have seen pictures of a top target shooter with a considerable cant in offhand. He is in a stable stance and makes the gun fit him.

Tubb shoots with a lot of cant. The key is that he's very consistent and also zeros his rifles with that exact same cant. I want to say that he has special sights that he uses, but I don't feel like digging his book out and going through it to verify.

The key is to be consistent. If you are going to shoot with cant, zero the rifle with the same cant you intend to shoot with. And if you zero the rifle with cant, shoot it with that same cant. If your sights aren't above the bore when shot/zeroed with cant, you will need to compensate for the cant when adjusting for range. A straight elevation adjustment won't do it.

 

[tangolima]

With a zeroed rifle and the dope card, in order to hit a target, I would do the following.

Range the distance and set the elevation. Clock the wind and set the windage. Fire and correct if needed. It is simple and natural to me.

I wouldn't like it if it becomes more complicated. Range the distance and set both elevation and windage. Clock the wind and adjust both windage and elevation.

With significant canting(>5 degree), the second scenario what I will have to deal with. It may work for somebody extraordinary, but never for me, who is an ordinary nobody.

Offset scope mount? I follow the same principle. 100yd poi is 1” to the right. If necessary I hold 1moa to the right. The hold in moa is diminishing with distance. If poi is right on at 100yd, the error is always 1moa. Well, in practice it may not matter a whole lot when you factor in wind correction. You need to change the wind hold on the fly anyway.

Now this is not counting the effect of muzzle climb before bullet exits bore. It would be even messier if I cant such rifle. I try not to cant so that I don't have to think much while try to hit that tiny soda can at 150yd with wind blowing. So I have level on every scoped rifle. I even put level on iron sight guns that I use to shoot a bit farther away.

-TL

Sent from my SM-N960U using Tapatalk

 

[JohnKSa]

Ok, found it. Per his book "Highpower Rifle", David Tubb sets up his sights on his high-power competition rifle with cant. He uses a bubble level to make sure he is holding the gun at the proper angle (a 7 degree cant for his prone shooting preference which matches how the sights are mounted to the gun) so that he's consistent.

The discussion is on page 95, but that's only a small part of it. To get the full picture of how he shoots, you also need to read the sections on offhand and seated shooting.

The point is that you just need to be consistent. If you are going to mount the scope to the rifle so they are both level and the scope is directly over the bore and then sight in the rifle with the crosshairs level, then you need to shoot with the crosshairs level in the field. That's the simplest solution, but not the only one.

 

[bamaranger]

level

Leveling the crosshairs is my most hated task in mounting a scope. I never seem to get it right the first time. Somtimes nor the second....or third.

 

[Shadow9mm]

Leveling the crosshairs is my most hated task in mounting a scope. I never seem to get it right the first time. Somtimes nor the second....or third.

Check out the real avid scope leveling system. Easy to use, great results.

 

[tangolima]

Leveling the reticle at home at a bench is very easy. A plumb line will do. The hard part is to keep it level when you shoot in the field. There may not be reference available. A simple bubble level installed on the rifle works great.

I didn't care about the bubble level. Installed one just for the heck of it. I was surprised to realize that my visual judgement was off most of the time, even grossly sometimes.

Does it make much difference? It depends.

-TL

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