Canting Vs Reticle Alignment Issue

[Die Judicii]

This particular issue is one that I've noticed many times over the years,,, and with quite a few different scopes.
And I'm wondering if others have noticed the same,,, and does anyone have any reasoning as to why ??
Is it due to the way the scope and reticle is actually made ?

I generally fit my own scopes,, but sometimes I've had them done at whatever gun shop.
If done at the shop/s they invariably sit a bubble level across the turret cap and then tighten accordingly.
But when I get home and have a close look,,, quite often it is canted.

I have a very good eye for levels that has never let me down.
Working in construction sites I'm spot on when compared/checked by spirit levels, water tube levels, etc.

So, if I set up a scope myself I get the rifle itself "upright" (as in,, not canting),,,, and then the reticle horizontal by sighting thru the scope,,, also with a
known horizontal plane off in the distance for reference purposes .
And then,,,, if you look at the turret cap itself ,,,, it is actually canted (off level)
And, if you set the scope by turret cap (level),,,,, then the reticle will be canted.

I've found some scopes are worse than others for this issue,,,, and definitely NOT cheap scopes.

When I've finished setting the scope with reticle vertical, and zeroed you can see that the turret housing itself is actually rotated slightly.

Anyone else noticed this ??

[Oldbloke]

Wouldn't that be telling you that the reticle within the scope was not installed level? e.g skewed

[bladeracer]

First up, it really doesn't matter if the reticle is square with the axis of the rifle, all that matters is that the reticle is plumb when you are shooting. If you tuck the buttplate into your shoulder pocket at a ten-degree angle then you need to twist yourself out of shape to get a plumbed reticle vertical when you shoot - it's better if you simply mount it at 10-degrees to suit yourself, so the reticle is plumb when you shoulder the rifle. You can mount the scope with the reticle at 45-degrees, and it will be just as accurate as a plumbed one, as long as you hold the rifle at 45-degrees when shooting.

In fact, if you could consistently hold the reticle at any angle, you wouldn't even need to hold it plumb, just at the same angle every time you pull trigger. Think of some of the old scopes that had just a center dot with no crosshairs to tell you what angle you are holding the rifle at. They rely on you holding the rifle consistently every time.

The scope also does not need to be vertically above the bore axis. If it's offset 30mm to the left to allow ejection or a straight bolt handle, just zero it 30mm left of point of aim and it will be 30mm left at all ranges.

It doesn't need to be low down as close as possible to the bore either.

Think of aircraft machineguns, artillery or tanks that have the sighting system far remote from their gun barrels. It makes no difference.

I'm the same as you, being a carpenter, I have an excellent eye for determining plumb, level, parallel and straight. I mount my scopes by eye.

I have had people pick up one of my rifles and exclaim that "the reticle is not plumb!", my response is "sure it is, you're just holding the rifle at the wrong angle!"

This particular issue is one that I've noticed many times over the years,,, and with quite a few different scopes.
And I'm wondering if others have noticed the same,,, and does anyone have any reasoning as to why ??
Is it due to the way the scope and reticle is actually made ?

I generally fit my own scopes,, but sometimes I've had them done at whatever gun shop.
If done at the shop/s they invariably sit a bubble level across the turret cap and then tighten accordingly.
But when I get home and have a close look,,, quite often it is canted.

I have a very good eye for levels that has never let me down.
Working in construction sites I'm spot on when compared/checked by spirit levels, water tube levels, etc.

So, if I set up a scope myself I get the rifle itself "upright" (as in,, not canting),,,, and then the reticle horizontal by sighting thru the scope,,, also with a
known horizontal plane off in the distance for reference purposes .
And then,,,, if you look at the turret cap itself ,,,, it is actually canted (off level)
And, if you set the scope by turret cap (level),,,,, then the reticle will be canted.

I've found some scopes are worse than others for this issue,,,, and definitely NOT cheap scopes.

When I've finished setting the scope with reticle vertical, and zeroed you can see that the turret housing itself is actually rotated slightly.

Anyone else noticed this ??

[Blr243]

I just grip th rifle the way it feels comfortable to me often with eyes closed so I don’t subconsciously wriggle my position to match the reticle . Then open my eyes, and while in the same position I spin the tube in loose rings until it looks plumb ....I see no point in locating the reticle in relation to an axis or plane part of the rifle

[GQshayne]

My father does the same as you - he always mounts his scopes crooked too!!

What I do to negate this, is put the level on the rifle and get it upright, and then mount the scope with the level. Can't be wrong then. And I think you will automatically have it perfect when you shoulder the rifle as your eye will determine the position.

[animalpest]

For decades I always mounted the scope to suit me and it looked straight for my eyes. My best mate always reckoned my scopes where crooked. Maybe they were, or maybe he just canted/shouldered the rifle different to me.

Having a scope fitted that is slightly canted doesn't much affect where the bullet will hit through to your sight in distance. But at long range it's a different story.

As an example, recently I sighted in my 25/06 at 100. Shot a couple of 0.25 inch group that was 1.25 inches high, ie zeroed for 200. Ok, now let's go back to 500 yards.

I put the 500 yard hash mark on the target and fired a group at the gong. Shots all missed - correct elevation, but all hit the dirt to the right.

If the scope is canted 3 degrees, that equates to over 6 inches out in the horizontal plane at 500. (The eye has a lot of difficulty seeing a 3 degree error).

What is happening is I am following the vertical line down on the crosshair and lifting the aiming point up to give the right amount of hold over. But the scope is canted so the vertical line is not in line with actual bullet drop (Bullets follow a straight line towards earth from gravity, excluding wind etc) and it falls to the right of the scopes aiming mark. The bullet won't follow your canted line to earth!

The same would happen if you dialed up the clicks on your scope.

To overcome this, level your rifle. Then put your scope on and use a level on the bottom flat area of the scope, below the turret. Level the scope and rifle together. Quality scopes use this as the place to level the crosshairs when assembling.

Some scope brands accept more than 3 degrees of misalignment in their cross hairs. Others (e.g Nightforce) have tolerances of less than 1.5 degrees.

So I leveled the scope and rifle, resighted the rifle at 100 and hit all my shots into the 75mm circle of the gong at 500.

To see this yourself, draw a circle and cross hairs on a piece of paper. Now move the paper so the crosshair is canted by say about 30 degrees. The bullet will fall directly to the bottom of the paper, it won't follow your canted cross hairs elevation point. Gravity.

[Die Judicii]

Thanks for the input fellas,
But I think some of you missed my point.

Putting it this way,,,,
Using just a scope on its own,, clamp or anchor it in position with the vertical part of the reticle lined up with the edge of a doorway on the far side
of a room or passage way, that you know is vertical.
Then while still clamped in position,,, sit a bubble level across the top of the elevation turret cap.
(Or underneath the scope if that is an option,, as AP described)

Chances are,, the bubble level will not show horizontal,,, indicating that the turret cap is not at 90 degrees to the vertical part of the reticle.

[scoot]

https://schmidtandbender.com.au/wp-cont ... 080-81.png
Neat, simple little tool that squares up the base of scope to the rail. Takes all guess work and farting about with tiny levels out of the equation. If the rail's square on the action and the scope is good, makes the job super quick and easy.

Won't help if the reticles not square In the scope though

[bladeracer]

No, I saw the point. I was just pointing out that since it's not necessary to have the reticle aligned with the axis of the rifle, there's no reason manufacturers need to align the reticle with any external surface of the scope.

Thanks for the input fellas,
But I think some of you missed my point.

Putting it this way,,,,
Using just a scope on its own,, clamp or anchor it in position with the vertical part of the reticle lined up with the edge of a doorway on the far side
of a room or passage way, that you know is vertical.
Then while still clamped in position,,, sit a bubble level across the top of the elevation turret cap.
(Or underneath the scope if that is an option,, as AP described)

Chances are,, the bubble level will not show horizontal,,, indicating that the turret cap is not at 90 degrees to the vertical part of the reticle.

[bladeracer]

For decades I always mounted the scope to suit me and it looked straight for my eyes. My best mate always reckoned my scopes where crooked. Maybe they were, or maybe he just canted/shouldered the rifle different to me.

Having a scope fitted that is slightly canted doesn't much affect where the bullet will hit through to your sight in distance. But at long range it's a different story.

As an example, recently I sighted in my 25/06 at 100. Shot a couple of 0.25 inch group that was 1.25 inches high, ie zeroed for 200. Ok, now let's go back to 500 yards.

I put the 500 yard hash mark on the target and fired a group at the gong. Shots all missed - correct elevation, but all hit the dirt to the right.

If the scope is canted 3 degrees, that equates to over 6 inches out in the horizontal plane at 500. (The eye has a lot of difficulty seeing a 3 degree error).

What is happening is I am following the vertical line down on the crosshair and lifting the aiming point up to give the right amount of hold over. But the scope is canted so the vertical line is not in line with actual bullet drop (Bullets follow a straight line towards earth from gravity, excluding wind etc) and it falls to the right of the scopes aiming mark. The bullet won't follow your canted line to earth!

The same would happen if you dialed up the clicks on your scope.

To overcome this, level your rifle. Then put your scope on and use a level on the bottom flat area of the scope, below the turret. Level the scope and rifle together. Quality scopes use this as the place to level the crosshairs when assembling.

Some scope brands accept more than 3 degrees of misalignment in their cross hairs. Others (e.g Nightforce) have tolerances of less than 1.5 degrees.

So I leveled the scope and rifle, resighted the rifle at 100 and hit all my shots into the 75mm circle of the gong at 500.

To see this yourself, draw a circle and cross hairs on a piece of paper. Now move the paper so the crosshair is canted by say about 30 degrees. The bullet will fall directly to the bottom of the paper, it won't follow your canted cross hairs elevation point. Gravity.

Using holdover instead of dialing the scope to the range to hold dead on introduces cant every time, regardless of whether you mount the scope plumb or not.

[Die Judicii]

No, I saw the point. I was just pointing out that since it's not necessary to have the reticle aligned with the axis of the rifle, there's no reason manufacturers need to align the reticle with any external surface of the scope.

Fair point, but for me personally its annoying when you've got your reticle plumb,, and its shooting the eye out of the needle,,,,,,,
to look down on the scope body from above or behind,, and see it is rolled to the left or right.

[bladeracer]

No, I saw the point. I was just pointing out that since it's not necessary to have the reticle aligned with the axis of the rifle, there's no reason manufacturers need to align the reticle with any external surface of the scope.

Fair point, but for me personally its annoying when you've got your reticle plumb,, and its shooting the eye out of the needle,,,,,,,
to look down on the scope body from above or behind,, and see it is rolled to the left or right.

Agreed, it just doesn't look right.

[animalpest]

Nope Bladeracer, it is the same whether you look along the vertical or use your scope clicks. Out of vertical is out of vertical no matter what method you use. They will both be out.

Even if you think your scope is correctly aligned by eye, you may be out by degrees

And then don't expect hold over to be correct without truing scope to action.

Have you ever sighted in a scoped rifle and had to go up (or down) and the next shots are left or right? Thought the scope adjustments move left or right when you adjust up or down? Maybe either the scope cant is wrong or you change the cant between shots.

Oh and turret caps are rarely an accurate level.

[bladeracer]

Nope Bladeracer, it is the same whether you look along the vertical or use your scope clicks. Out of vertical is out of vertical no matter what method you use. They will both be out.

Even if you think your scope is correctly aligned by eye, you may be out by degrees

And then don't expect hold over to be correct without truing scope to action.

Have you ever sighted in a scoped rifle and had to go up (or down) and the next shots are left or right? Thought the scope adjustments move left or right when you adjust up or down? Maybe either the scope cant is wrong or you change the cant between shots.

Oh and turret caps are rarely an accurate level.

I'm not seeing any way that the scope can know or care what angle the rifle is at. The scope only knows scope stuff, the rifle only knows rifle stuff.

Looking at my example with the scope offset to the left, as is commonly done on top-eject levers, and military sniper rifles that need to feed or eject vertically, or have straight bolt handles that rise vertically above the action. How do snipers hit their targets when their reticle has no bearing on the angle of the rifle?

I recall, when I did this with one of my own rifles (30mm offset to the left), that I saw a forum post somewhere. A guy had set his up with the scope offset the standard way, but angled the reticle so it pointed directly down to the bore axis. He simply held the rifle at an angle to keep the reticle plumb. I vaguely recall he did this with a Type 99 Arisaka, but it was a few years ago now

[deanp100]

And how accurate are little levels an inch long.

[Die Judicii]

Oh and turret caps are rarely an accurate level.

Exactly my point AP,,,,,,

But so many of the gun shop staff insist on doing it that way which is why I invariably set my own up,,, my way.

[Die Judicii]

And how accurate are little levels an inch long.

Agreed,,,,,,
When I do resort to using a bubble level,, I use my 6" engineers level.

[disco stu]

Problem I see with dialing scope for range adjustment if the turret and cross hairs aren't aligned is that this will induce a shift left or right also, as the vertical turret (which isn't exactly vertical) will move the cross hair at a slight angle, the angle that the turret is on.

[animalpest]

Yes Disco stu, some scopes reticle are not aligned with the body of the scope.

So long as the reticle is correctly vertical and horizontal, it doesn't make any difference when shooting.

It only make it more problematic when trying to get the vertical line straight with the border axis.

[Biscuits]

Levelling a scope takes me at least half an hour. I check it, check it again, put the rifle in a different position check it again, slowly tighten the screws, check it several times.

This is probably why the shop is a bit slap dash; they do their best in the 5-10 mins they allocate to the task.



I’ve also noticed it is very difficult to tell a reticle is level by eye. Your eyes will play tricks on you, depending what your head position is.

[bladeracer]

Levelling a scope takes me at least half an hour. I check it, check it again, put the rifle in a different position check it again, slowly tighten the screws, check it several times.

Why? What are you trying to achieve?

[animalpest]

Already been clearly explained.

[niteowl]

Already been clearly explained.