Vertical alignment of Rifle and Scope?

[elkhunter11]

Regardless of who you are, canting the rifle will result in a horizontal offset. What does vary, is how much offset there is, and how you deal with it. One degree will only result in around .010" of offset for the average scope/rifle setup, so one or two degrees will mean nothing to the average big game hunter. Now if you cant the rifle 30 degrees, that is about 1/3" of offset , so if you zero at 100 yards, it means an error of about 1-1/4" at 500 yards. But if you set your horizontal zero at 250 yards, the error is only 1/3'" at any point within 500 yards.

[traderal]

My biggest beef is the disconnect with the whole gun industry on making a system that allows an almost perfect alignment of the scope over the bore. The weaver rings and bases, Z-rings, even the Leopold bases and rings once mounted are canted off center. Tighten the screws on the scope and the torque rotates the scope crosshairs out of alignment. I call it all garbage. At least once in my life I had a bench rest rifle that had the mounts and receiver machined from one block of metal. That was a nice quick and easy setup.

[Pathfinder76]

Originally Posted by elkhunter11

Regardless of who you are, canting the rifle will result in a horizontal offset. What does vary, is how much offset there is, and how you deal with it. One degree will only result in around .010" of offset for the average scope/rifle setup, so one or two degrees will mean nothing to the average big game hunter. Now if you cant the rifle 30 degrees, that is about 1/3" of offset , so if you zero at 100 yards, it means an error of about 1-1/4" at 500 yards. But if you set your horizontal zero at 250 yards, the error is only 1/3'" at any point within 500 yards.

Again, your rifle can be canted. Bores are round. Gravity is constant. Your crosshairs need to be level to the target.

[marky_mark]

Oh understand the science behind it
But why would you intentionally induce cant?
If your using a moa base of any sort it will through your tracking off
If your using a level that’s integrated into your rings it’s pretty much useless

The title of the video is “ why the Tubb bubble level is a must for accurate shooting”
I use levels on all my rifles. I Found that solved a lot of problems to just level everything
Do you use levels especially if your inducing cant intentionally?

[Salavee]

Originally Posted by traderal

My biggest beef is the disconnect with the whole gun industry on making a system that allows an almost perfect alignment of the scope over the bore. The weaver rings and bases, Z-rings, even the Leopold bases and rings once mounted are canted off center. Tighten the screws on the scope and the torque rotates the scope crosshairs out of alignment. I call it all garbage. At least once in my life I had a bench rest rifle that had the mounts and receiver machined from one block of metal. That was a nice quick and easy setup.

I find that a real pain as well. I found I have to give the torque some "lead" to get it right. Usually takes more than one attempt to get the proper alignment, even with the best of them. Don't know what the fix is. Maybe Richard Near.

[catnthehat]

Originally Posted by marky_mark

Oh understand the science behind it
But why would you intentionally induce cant?
If your using a moa base of any sort it will through your tracking off
If your using a level that’s integrated into your rings it’s pretty much useless

The title of the video is “ why the Tubb bubble level is a must for accurate shooting”
I use levels on all my rifles. I Found that solved a lot of problems to just level everything
Do you use levels especially if your inducing cant intentionally?

Inducing consistent cant is important in Maintaining natural alignment , which is mandatory to maintaining shot to shot accuracy.
Cat

[elkhunter11]

Originally Posted by chuck

Again, your rifle can be canted. Bores are round. Gravity is constant. Your crosshairs need to be level to the target.

The horizontal offset has nothing to do with gravity, or the shape of the bore, it's simple geometry. And even though the scope adjustments will not be affected, as long as the scope is level. if the rifle is canted, there will be a horizontal offset. Unless the crosshairs are directly above the bore, the windage can only be correct at one distance. An extreme example would be a side mount scope used on a top eject model 94, where the crosshairs are offset horizontally, the scope adjustments work normally, but the windage can only be correct at one distance.

[Pathfinder76]

Originally Posted by marky_mark

Oh understand the science behind it
But why would you intentionally induce cant?
If your using a moa base of any sort it will through your tracking off
If your using a level that’s integrated into your rings it’s pretty much useless

The title of the video is “ why the Tubb bubble level is a must for accurate shooting”
I use levels on all my rifles. I Found that solved a lot of problems to just level everything
Do you use levels especially if your inducing cant intentionally?

You obviously missed everything said.

[YYC338]

Exaggerate the issue to see the geometry. Kant the rifle 80 degrees clockwise, mount the scope so the HZ crosshairs are HZ. Zero the rifle at 100 yards lets say while holding the scope "level". Lets assume the rifle is very accurate and groups well within a minute of an angle.

Shoot at a 400 - 500 yard target with no hold over. Where will the bullets impact? How many think they'll be low but inline with the vertical center line of the target (more or less)?

How many think they'll be low and to the right of center?

Assuming they'll be right of center, if you re-zeroed at 400 where will the bullets impact at 100? High only or high and left?

[Dean2]

Originally Posted by elkhunter11

The horizontal offset has nothing to do with gravity, or the shape of the bore, it's simple geometry. And even though the scope adjustments will not be affected, as long as the scope is level. if the rifle is canted, there will be a horizontal offset. Unless the crosshairs are directly above the bore, the windage can only be correct at one distance. An extreme example would be a side mount scope used on a top eject model 94, where the crosshairs are offset horizontally, the scope adjustments work normally, but the windage can only be correct at one distance.

Elk, your offset mounted scope example proves you are not correct. In the absence of wind and discounting the rotation of the bullet in flight, bullets do no travel left or right of their flight path. If your vertical crosshair is offset even a full inch that horizontal offset of the bullets flight path to your line of sight remains the same at all distances, as long as the scope is perfectly parallel to the rifle bore. The line of sight and the bullets path, just like two parallel train tracks do not get closer together as the distance increases, it is an optical illusion. They also don't get further apart.

[elkhunter11]

Originally Posted by Dean2

Elk, your offset mounted scope example proves you are not correct. In the absence of wind and discounting the rotation of the bullet in flight, bullets do no travel left or right of their flight path. If your vertical crosshair is offset even a full inch that horizontal offset of the bullets flight path to your line of sight remains the same at all distances, as long as the scope is perfectly parallel to the rifle bore. The line of sight and the bullets path, just like two parallel train tracks do not get closer together as the distance increases, it is an optical illusion. They also don't get further apart.

That one inch you mention is the horizontal offset that I am referring to. And you are correct, you can adjust the scope to maintain that 1" of horizontal offset at multiple distances, but how many people purposely leave their windage out by 1" . Everyone will set the horizontal offset to zero at some distance, and it can only be zero at one distance. Now if the crosshairs are directly above the bore there is no horizontal offset, and the windage can be correct at multiple distances.

How many people do you know with offset scopes that don't set the windage to zero at some distance? And by doing so, they introduce the angular error that I am referring to.

And if you go back to post #20, I mentioned being able to adjust the scope to produce the same horizontal offset at multiple distances. If the bore and crosshairs are perfectly parallel, that will be the result, but the scope won't be zeroed horizontally, at any distance.

[CNP]

As already mentioned BDC reticles are critical to being mounted "level". I have an RZ600 reticle on one of my rifles. It certainly has to be mounted level and on a levelled rifle or the POI will be "off in the bushes" . OP pun intended.

not like this:



like this:

[elkhunter11]

Originally Posted by YYC338

Exaggerate the issue to see the geometry. Kant the rifle 80 degrees clockwise, mount the scope so the HZ crosshairs are HZ. Zero the rifle at 100 yards lets say while holding the scope "level". Lets assume the rifle is very accurate and groups well within a minute of an angle.

Shoot at a 400 - 500 yard target with no hold over. Where will the bullets impact? How many think they'll be low but inline with the vertical center line of the target (more or less)?

How many think they'll be low and to the right of center?

Assuming they'll be right of center, if you re-zeroed at 400 where will the bullets impact at 100? High only or high and left?

The point of impact can be centered horizontally at one distance, and only one distance, because of the horizontal offset, so the bullets will only hit the vertical centerline at 100 yards.

[Salavee]

Originally Posted by elkhunter11

The point of impact can be centered horizontally at one distance, and only one distance, because of the horizontal offset, so the bullets will only hit the vertical centerline at 100 yards.

Something to be said regarding the correct amount of Cast On or Cast Off on a rifle stock, isn't there ?

[elkhunter11]

Originally Posted by Salavee

Something to be said regarding the correct amount of Cast On or Cast Off on a rifle stock, isn't there ?

With the rifle pretty much on it's side, as in the example I was responding to, cast won't matter. But this example does show how asinine it is to hold a handgun horizontally while firing it, like the gang bangers on television.

[Salavee]

Originally Posted by elkhunter11

With the rifle pretty much on it's side, as in the example I was responding to, cast won't matter. But this example does show how asinine it is to hols a handgun horizontally while firing it, like the gang bangers on television.

Absolutely it does. The same goes for rifles. Any amount of cant will show up on a target at some distance from the muzzle.

[Salavee]

Tilt a rifle 90 degrees and your verticle crosshair now becomes the horizontal crosshair. Any cant induced between 0 deg and 90 deg , regardless of the amount will show up at some point in the trajectory.

[YYC338]

Originally Posted by Salavee

Tilt a rifle 90 degrees and your verticle crosshair now becomes the horizontal crosshair. Any cant induced between 0 deg and 90 deg , regardless of the amount will show up at some point in the trajectory.

Or more correctly, I would think it will show at every point in the trajectory except the zero point. The further from the zero point the greater the the deviation. More difficult to detect near the zero point and also at slight deviations from zero degrees.

[Salavee]

Originally Posted by YYC338

Or more correctly, I would think it will show at every point in the trajectory except the zero point. The further from the zero point the greater the the deviation. More difficult to detect near the zero point and also at slight deviations from zero degrees.

Yes, it will be detectable at every point. The further it goes, the more pronounced it becomes. If the zero point was established using the identical cant that would be true.

[AndrewM]

Your crosshairs need to be level. Not your rifle.[/QUOTE]

Chuck is correct. Level your scope to your target. Most people have a natural cant and consistency is the most important part.

[CNP]

Originally Posted by AndrewM

Your crosshairs need to be level. Not your rifle.

[/QUOTE]

Not if the scope has a BDC reticle. The verticle subtensions on a BDC scope must be aligned with the barrel in order to be accurate. If the scope is not mounted level, on a leveled rifle, the vertical subtensions will be off.

[AndrewM]

Not if the scope has a BDC reticle. The verticle subtensions on a BDC scope must be aligned with the barrel in order to be accurate. If the scope is not mounted level, on a leveled rifle, the vertical subtensions will be off.[/QUOTE]

Why? If you crosshairs are level with the target it doesn’t matter.

[Pathfinder76]

Not if the scope has a BDC reticle. The verticle subtensions on a BDC scope must be aligned with the barrel in order to be accurate. If the scope is not mounted level, on a leveled rifle, the vertical subtensions will be off.[/QUOTE]

This is simply not the case. The scope needs to be level with the target and all of your subtensions will be correct.

[CNP]

Originally Posted by AndrewM

Not if the scope has a BDC reticle. The verticle subtensions on a BDC scope must be aligned with the barrel in order to be accurate. If the scope is not mounted level, on a leveled rifle, the vertical subtensions will be off.
Why? If you crosshairs are level with the target it doesn’t matter.

Look at the reticles I placed on post #42 If you place the 600 yard subtension on target the POI will be off in the bushes to the left.

[AndrewM]

Originally Posted by CNP

Look at the reticles I placed on post #42 If you place the 600 yard subtension on target the POI will be off in the bushes to the left.

If your scope is level to the target it will always look like picture two. Doesn’t matter how much your rifle is canted as long as it’s consistently canted.

[CNP]

Originally Posted by AndrewM

If your scope is level to the target it will always look like picture two. Doesn’t matter how much your rifle is canted as long as it’s consistently canted.

No, you aren't grasping it.

[AndrewM]

Originally Posted by CNP

No, you aren't grasping it.

That’s because you are simply wrong. Move a level target from one distance to another and keep it level. If your crosshairs match the target, it will always track perfectly.

[CNP]

Originally Posted by AndrewM

That’s because you are simply wrong. Move a level target from one distance to another and keep it level. If your crosshairs match the target, it will always track perfectly.

Now Andrew you should think about it some more. A lot of guys already posted their opinion on this. This will change your mind, mostly because it's not from me. I can't make you under stand this.

https://www.americanhunter.org/artic...hy-it-matters/

[AndrewM]

Originally Posted by CNP

Now Andrew you should think about it some more. A lot of guys already posted their opinion on this. This will change your maid, mostly because it's not from me. I can't make you under stand this.

https://www.americanhunter.org/artic...hy-it-matters/

You are wrong. No how many times you try to repeat yourself. Think about this. How does a side mount scope track if you need to be level above the bore?
How do you find level on something round?

[CNP]

Originally Posted by AndrewM

You are wrong. No how many times you try to repeat yourself. Think about this. How does a side mount scope track if you need to be level above the bore?
How do you find level on something round?

I gave you and out and you threw it away. You don't believe the link I posted? You're a special...…………………...guy.


Can someone else explain it to him? I think he needs to know...