I just googled you're reference and only 1 came up so maybe it was the one you watched. NO!

The number #1 issue I saw (or didn't see) was he did not show the rifle being leveled and it was not held tightly in place (you can see it shift several times). Why would you install a level scope on an unlevel rifle? Why would you not fix the rifle so it can not move so as to ensure your work competent?

Issue #2 was how he arranged the scope and rings.
   a. He was moving his head back and forth, to adjust ER and not the scope. I always close my eyes and get a comfortable position on the rifle. Then, open my eyes and determine if I need to move the scope based on this. I'll move the scope and repeat.
   b. He did not push the rings forward so the recoil lugs where tight against the rail notch (recoil will move the scope forward).
   c. I always verify ring alignment, prior to installing the scope. Too many factors that could damage a quality optic.

To be honest, I'm not sure what roll the cards were playing. Alternately tightening the right & left side screws, all while watching the level, will ensure the scope stays where it should.

Now for the real answer. Yes, I use playing cards to aid in leveling my scopes. Before I mount the rifle in a rest, I will find the correct ER, as mentioned above, and take a measurement to the bell from the muzzle. Much more comfortable doing it now than trying to get a proper cheek weld once the rifle is mounted. Once the rifle is mounted and fixed, in the rest, I will use playing cards under the feet, to level the whole assembly. I also put a piece of large format paper on a wall (my garage door), about 40' away, and, using a 4' level, draw a plumb line in the center of the paper. This is what I use to plumb the crosshairs and not a torpedo level on the scope body. Notice I said plumb and not level? You need the scopes elevation knob to be precisely plumb in order to track long shots properly. Yes, a high quality scope should make this point moot, but, regardless, you will need a line on the paper and plumb is what I favor.

After the scope is properly tightened, I will draw a level line, about the center of the plumb line, to aid in getting a "close-enough" zero. Just peek down the bore and center it on the paper's "crosshair". Adjust the rifle's windage and elevation knobs to center.

There are different ways of doing it, but certain items which must be done to ultimately achieve a proper setup.

Never heard of the card trick.  I use to align with a level set up about 20 yards away from the gun and they never seemed to be just right.  Finally broke down and bought the wheeler pro scope leveling kit and have been very happy.  That being said I find that nothing best taking time to set everything right, slowly tightening mount screws, and if it isnt right just do it again.

I've leveled a few using a feeler gauge between the flat of the scope body and the top of the rail.  Of course, this only works if the reticle is level with the flat of the bottom of the scope body.  Same concept of the card trick, but I prefer the rigidity of the steel feeler gauges.  I've used a digital level on the scope VS the rail too, and just matched them.  Both methods have worked well for me.

Cards are my method, even got a nice slippery, new deck just for it.....getting them out is a bitch sometimes.

I do use levels to double check it, and so far they've been right.

I suppose it shouldn't be called "leveling"......since you're "paralleling"

Since your not actually using the reticle, but the scope body, I would think it could be inaccurate if the scope wasn't assembled perfectly.

I learned about a deck of cards a couple years back.  I use that and feller guages.  Works just as good as hanging a string w a weight.

       http://arisakadefense.com/collections/tools/products/optic-leveler-combo
 

Or you can buy a lifetime investment and get a Wheeler scope level kit. The right tool for the job does wonders.




 

You don't want the rifle level when you mount a scope. You want the scope's reticle and turrets level TO THE HORIZON. The way you do this: mount your rifle the way you would when shooting in your most common/basic position. Let's say it's prone. Get comfortable so you have a Natural Point of Aim. In this position, the rifle is probably not level. Then mount your scope in this position such that the reticle tracks to the horizon. Done.

Why?

Because if you mount your scope level to the rifle and then shoot with the rifle canted, you have now introduced vertical and horizontal error in your POI.

The bullet does not care if the rifle is level. Your barrel is round. Don't matter if you shoot with the rifle laying flat. The bullet only cares about gravity. Gravity is always down. The reticle needs to track correctly up/down and left/right with gravity.

I'm sorry, but I can't agree w/ any of this.
If you don't level the rifle, when plumbing the reticle, your scope adjustments will NOT track correctly.
You want the centerline of your bore and optics to be on the same vertical plane.
Let's say you cant the rifle CCW, before plumbing the elevation line of your scope.
You can certainly go out and zero your rifle at, let's say, 25yds.
Now, if you move to 100yds you'll have to also use windage adjustments to get back into the X ring.
This is because your centerlines are now on 2 different planes, horizontal (elevation adjustment) and vertical (windage adjustment).

Once your rifle is canted passed 45*, your elevation dial just became your windage. Doesn't seem like a proper way to track a round.

If you have a rail gun and always shoot at the same distance, then it doesn't matter where you put your scope, so long as it is properly leveled.

Visuals of Cant Error Trajectories

Yeah.  That's wrong.  Picture what would happen your way if the rifle was canted 90 degrees to the left and you'll see the problem.

Not if the reticle is out of alignment, which is often the case, even on high end scopes.

First get 3 bubble levels:

1x String / Line style bubble level
1x Flat bottomed style bubble level  
1x Round bottomed bubble level

Take your round bottomed bubble level and place in in the center of your rifle where scope will mount and level in in a vice, bench, or bags. Attach a rubber band to the string / line style bubble level so you can stick it on to the end of the barrel like a poor mans wheeler engineering kit and level it to match the round bottomed level. Now you can take the round level off and mount your scope. If your rifle rotates you will see it move on the string / line level. Take the scope and place the flat bottomed level on the top turret cap and level the scope. Tighten the rights and your done.

If your scope cross hairs are canted or you are super OCD about the cross hairs being exactly perpendicular to the horizon then you can use a plumb bob to level the cross hairs.

Y'all aren't grasping what I'm saying. You and the guy above you (who is talking about a canted rifle + a canted scope). But that's ok, Your reticle and turrets need to track level with the horizon (gravity). But your rifle doesn't. If you can't figure that one out, so be it. Enjoy your shooting, guys! :)

Here, take it from an expert: http://www.scout.com/military/snipers-hide/story/1540059-canted-rifle-level-scope

Canted rifle + scope level to the horizon = ok
Canted rifle + scope level to the rifle = bad

If you mount your scope level to the rifle and then shoot with a canted rifle... that's bad. I think we can all agree on that.
If you mount your scope level to the horizon (gravity), but your rifle is canted when you mount it, and you shoot with that same cant... that's ok. That's what I'm talking about. Nobody naturally shoots with a level rifle. Because our bodies are not level. We have curves and angles. A Natural Point of Aim is typically not a level rifle. You want the rifle addressed such that it's comfortable and such that you don't use muscle to keep your rifle in position. That position is usually not level. So.. what do you do? You don't worry about it. You mount your scope level with the earth and be done with it. Forget about the rifle.

You should be mounting your scope to your rifle with a NATURAL HOLD. That is a Natural Point of Aim. That means your rifle might be canted slightly to fit your shoulder pocket. This is ok. When you do this, mount your scope level to the horizon. Level to gravity. You do this with a plumb bob. Easy. Done. Now when you go shooting, your rifle fits your Natural Point of Aim and your scope/reticle/turrets are LEVEL. But your rifle doesn't need to be. Because the bullet doesn't know the difference. I'm not saying you need to shoot with your rifle canted. I'm saying this over OCD obsession with a level scope to a level rifle is nonsense. And the article I quoted explains it all.

Other options:

1. Always use a bubble level, even when you shoot. The con of this is it's annoying. It's time consuming. And it's not always as accurate as your brain (see the above link).
2. Use an adjustable butt plate to fit your shoulder better.
3. Ignore all of this advice and do whatever you want :)

i disagree that the brain is more accurate than a bubble level.    it may be capable of detecting extremely slight misalignment on picture frames when you're standing straight up in a room with level floor and ceiling as a reference.   but when your head is leaning over looking through a scope, and you are laying on a sloped hill and your target is on a sloped hill, as is almost always the case in this part of the country, i'll bet money nearly everyone will not be able to tell what's level and what's not.  i say that because I've RO'd an awful lot of matches with hundreds of shooters passing through the stages noticeably canting their rifles.

despite that, i think a lot of people are over thinking this. and i agree the only really important part is getting the reticle/scope level with the Earth's gravity, which means you need a plumb line, and not much else.

Gravity is the major force acting upon the projectile, so the most important thing is to align the vertical reticle in perfect alignment with the
gravitational plane. If you can accurately and repeatably cant the rifle (for ease and comfort) to the exact angle and adjust your scope accordingly, then great.

However, I find that the more variables I eliminate, the better I shoot. I use a machinists adjustable parallel to align the scope mount and the
flat scope bottom parallel. Think of the Spuhr scope mount. The mount comes with a mounting tool to do this exact same thing, sliding it in the
milled-in notch in the base of the scope mount until it levels the scope perfectly in the mount.

Maddawg

Totally agree with this...

77

What ultimately matters, 2 things:
1 - the scope is mounted on the rifle so that the windage adjustments are parallel to the horizon, and the elevation adjustments are perpendicular to the horizon. Per many explanations above, this insures the adjustments and bullet trajectory are aligned properly.
2 - with the scope mounted properly on the rifle as outlined above, the rifle has a mechanical indicator (like a bubble level) to let the shooter know that the rifle is being positioned/held to properly align the scope as outlined above. This insures that the rifle, and by default the scope, are aligned properly.
Yes you could have the rifle setup in a canted orientation, with the scope mounted in a proper orientation, and as long as there was a level on the scope to insure proper positioning, it would work. But generally speaking, shooting the rifle in a canted orientation can lead to issues with NPOA, recoil management, etc. There is a reason they make adjustable buttplates, so you can fit the rifle properly, and you don't have to shoot a crooked rifle!  

How do you accomplish this?
1 - install a mechanical indicator (like a bubble level) on the rifle, this establishes a baseline for the rifle. Best option is a clamp on bubble level for the mounting surface/rail. When in doubt, double or triple check this with multiple levels.
2 - create/setup an aiming reference, both a vertical & horizontal reference are best. Use something like a plumb-line, setup a grided target with a level, etc.
3 - clamp/hold the rifle so the mechanical indicator on it is level, look through the scope, and align the reticle with the aiming reference. Use whatever kind of sand bags, rests, etc that you have to hold the rifle steady.
4 - once the scope is aligned, make a number of reference indicating marks on the rings/mount and scope tube, to create a clear indication of where the scope needs to be in reference to the rings. Use a silver sharpie marker, it will come off with a little alcohol on a q-tip once you are done.
5 - tighten down the rings/mount, making sure the reference marks on the scope body and rings stay in alignment. This process of using indicator marks beats trying to visually hold it in alignment, as you try to tighten the rings/mount without it coming out of alignment.
6 - with the rifle indicating level, and the scope rings/mount tight, recheck against the aiming reference.

Once that is complete, you will need to shoot a "Tall Target" to confirm the alignment (and the tracking of the scope).
http://bulletin.accurateshooter.com/2015/11/calibrate-your-clicks-with-tall-target-test/
https://www.youtube.com/watch?v=12Wf0Cuwwi8
If you find an error in the Tall Target Test, you will have to determine if the error is due to a cant induced or scope tracking error. If you remount the scope, and the error still exists, then it is most likely a tracking issue.

The above method works 100% of the time, assuming the operator does the alignment process correctly.

All other methods are potentially prone to some degree of error:
- Feeler Gauges or Playing Cards, these methods all rely on the rifle surface and scope surface that they are place against being 100% true & level. With very high-end components that may be the case, but it is definitely not the case with many low end components.
- Wheeler Engineering Kit, this relies on the operator setting up the reference level on the rifle properly, and the surface used for the scope level being 100% true & level.
In 20+ years of mounting scopes, I have learned the hard way that too many parts of the scope (turret cap, adjustment housing, etc) are NOT as true or level as people assume, and this commonly leads to errors. These methods are also susceptible to error if the reticle/adjustments are not true to the flat surfaces that are being used as references during the mounting process.

You can use the methods above as a "starting point", but you still need to visually check the finished product against an aiming reference and shoot a Tall Target Test to confirm everything is aligned properly.

I would say that about 50% or more of the students that show up to one of my classes come with a scope that is mounted with some degree of cant. When they come into the classroom I have an aiming reference setup for the first check. When we hit the range the first thing they shoot after some warm-ups and zero confirmation is a Tall Target Test, where we usually find some problems!

If I had a dollar for every time I saw someone blame a long range miss on a wind condition or DOPE error, when in reality it was a cant induced aiming error, I would be very rich!

The shooters that have the best results at long ranges are the one who:
- have a dead nuts zero. A lot of shooters have a 1/8-1/4 MOA error that they don't realize is there, usually because they rely on a single 3-5 shot group for confirmation.
- run extensive Tall Target Testing, both to identify cant and tracking errors. A lot of scopes have some form of tracking error, which many shooters just write off to being some other issue.
- always confirm they have zero cant in the rifle/scope when shooting. A cant error that many shooters could not detect without a level, could easily cause a miss at long ranges.
Once again too many shooters are too quick to blame something else like wind, for what is in reality and aiming error.

You could have the rifle canted all you want long as the scopes parallel to the horizon. Parallel to the horizon what position your rifle is is irrelevant.

Running tracking tests are for pussies. Its way more exciting when your scope is always testing ya.

I bought the same set up. Works great same as feeler gauge  and deck of cards. They all work as long as the scope that you have has a flat bottom.

I f that is a fact then why does my wheeler scope mounting kit include leveling for the rifle and the scope?

Because it doesn't hurt. Some people like to cant their rifles, some dont. Only thing that matters is that your crosshairs aren't canted to the horizon.

Are canted rifle does make a difference sooner or later.

I prefer to use a feeler gauge. Much thinner options available than the thickness of a card.

This.

The tool above is optimal IMO.

I also used feeler gauges which can work.


However...it assumes a quality scope that has a level base that is square to the reticle and that the rail on the upper is flat as well...

Its only as true as the surfaces you are working off of.  

Life got much better when I gave up fighting with cheap optics and bought real glass...

The purpose is to level the scope to the rifle. Not the rifle to the horizon, or the scope to the horizon.

It seems to me that the card method should work well. Not as good as the commercial options, but there seems to be less variability than using plumb lines.

Keep in mind, cos(10degrees) = .985. This means that your adjustments will only be off by 1.5% if you can eyeball it to within 10 degrees, which is pretty easy. I'm not saying to be this cavalier, just keeping the problem in perspective.

I have heard a couple of people explain it to me like that, but I still can't wrap my brain around it.

If the rifle and scope are not 'plumb' with each other, the bullet won't fly straight up (to its apogee) and straight back down--it will go left or right (depending on which way the gun is canted).  And if it does this, nothing will line up with the vertical stadia line further down range.  If I cant an AR15 45* to the left for whatever reason, because the barrel is normally physically pointed up (to achieve an arc to the bullet), It will now be physically pointing slightly to the left, and I will get a group that prints low left down range--I have taken out some of the elevation I would normally have, and added a lateral component to it.  You could only theoretically zero that rifle at one distance if you did that, as the bullet is not just rising and falling straight up and down, it is physically moving laterally as well.  It may not be quite as dramatic on a bolt gun because the sight is closer to the bore, but it would still be there, wouldn't it?  The AR example is pretty easy to reproduce, which is why I used it.  Maybe I'm just not understanding though--in my defense, I'm kinda dumb.

There was some 800lbs brain discussion on this topic over at the hide.  

David Tubb did some solid real world work with this and he intentionally doesn't mount his optic directly above the bore.  It is not in line...or even close to it.

Yet, he gets hits and wins.

I don't get it.  It seems wrong to me...but they all eventually came to the conclusion that the reticle needed to be flat with the horizon.  The rifle could be canted under it without a problem.  

It seems wrong to me...but they had no shit engineers and experts doing it and it worked.

If my rifle has a rail, I use the arm of my caliper to level the scope.

I understand this. Rotate the rifle as much as you like, the bullet doesn't care. As long as the scope is level to the horizon, which angle the barrel is at doesn't matter.

That said, I'd still level the scope to the rifle more or less. Wrong-hand, alternate positions, etc. This also helps if you have no clear view of the horizon. Say, for example, you are shooting down into an Afghan valley. You can still feel gravity and orient your rifle correctly, and thus get the scope more or less properly oriented with gravity.

Post a link to the hide topic?

Imagine in your brain holding the scope and gun perfectly level with the horizon and still. Now, the rifle barrel rotates around and around. It doesn't matter, because it's still pointed in the same direction.

As far as rotating the ENTIRE RIFLE, I think you're right, that the "upward angle" becomes now canted one way or the other. The only way I can figure to correct this is to zero with an offset from the bore axis (while rifle is rotated) to the scope axis.

It would be really weird to have to add windage to my drop calculations just because.

Coriolis effect is real at 300 yards....dial that shit.

This does an excellent job its sort of a copy whats built into the spuhr mount design . The only time it failed me was on an aero lightweight mount that would torque the optic so badly (about 15-20 degrees no mater how I tightened the rings) I had to fight with it for awhile and break out the levels to get it right. On quality rings where you can torque the rings down nice and evenly it works great.

I've done several of the methods described in this thread.

I'll just say, whatever method you use, do a tracking test to confirm your scope isn't all jacked up.

Holy crap. I need to sit down and re-read all of this.

Found this: Levelling your scope to the fall of gravity.

same as feeler gauge between the flat of the scope body.... it works

separate issue that needs fixed....

"And it's not always as accurate as your brain"

not true.... 

only true on flat level ground looking at a flat level target..... 

as soon as you change those 2 factors, your brain is useless.... i see it all the time in classes.... people will "feel" level, then i have them look at their bubble lvl and see how off they are

Well, there's your problem right there!  

I just this weekend mounted a scope on a new Remington 700.  The deck of cards method worked perfectly although I do admit also using a pair of small levels to assist the process although my technique with the levels was not "meticulous".  For this particular application, all I want is the scope pretty close to "true" as I have a scope tube bubble level which I will be installing and adjusting to perfection for use when needed.  For my purposes, as long as the reticle is square when the trigger is pulled, it doesn't really matter if the rifle is "canted" a few degrees.

Brick walls and roof lines are good sources of true to earth level lines but you need to be perpendicular to wall/roof line. If the rifle is supported in a level position then view a brick wall or roof line to check reticle level. I usually set receiver on a level and shim to get it level. 

What you've described so perfectly is a recipe for ensuring the rifle is in fact canted.

There's a place for that, but that's for a prone or 3 position target shooter, who is shooting at a single, known distance.   That's because under those known conditions the resulting canting error can be zeroed out with the sights.  In this one very specific case, the benefits of consistently holding the rifle help improve accuracy, but openly because the effects of canting error have been negated by the constant, known distance to the target and the related sight adjustments in windage and elevation to zero the rifle at that one range, for the canted condition.  


However, for a precision shooter who plans to engage targets at varying ranges, canting the rifle is a major problem.   It's a problem because the change in horizontal and vertical impact due to the canting error varies with the range in a curvilinear manner with the magnitude of the error getting worse as the range increases.

----

Now...to be fair, I've heard hunters etc say this kind of "hold the rifle naturally and adjust the scope so it's level with the horizon" crap since I was 12 (40 years ago at this point).  Unfortunately, the fact that it's a popular and long standing myth doesn't make it correct.  Google "ad populum logical fallacy" if you're not understanding the difference between a concept being popular and wide spread and being correct.

I'm a little picky when it comes to leveling the scope.

1. I start by leveling the rifle.  This requires a level surface on the rifle.  The scope base can work, provided the receiver has been drilled and tapped so that the holes are on the centerline of the receiver. That's not always the case.    Sometimes a tang will work.  Sometimes you'll need to remove the rifle from the stock and use the bottom of the receiver, etc.


2. I then install the rings and check to see that the tops of the bottom halves of the rings are also level. If they are not, and the receiver is level, it tells me the receiver was not D&Td on center.  If the tops of the rings are level, I can put the rifle back in the stock and proceed from there.  


3.  I then install the scope in the rings and adjust it fore and aft in the rings as needed to get optimum eye relief to accomodate prone, sitting and off hand positions.


4.  I level the cross hairs.  Some people use a level placed on the adjustment turret, and it's better than nothing.  However, the scope turret top however may not be completely parallel to the horizontal cross hair.  It works for ball parking the leveling of the scope but you need to use a plumb line to get it right.

You can use the edge of an interior wall except not all walls are as square as you'd think.  For example, I did some remodeling in the bathroom to remove the unused tub and replace with a large shower and removed the small shower and converted it to closet. I discovered that the top and bottom of the wall was 1/2" out of plumb, and had to order the mirrored closet doors cut accordingly.

The side of a building works better, on average, but you still have no guarantee of perfection.  You can also use a bubble level and draw a plumb line, but that introduces some variance based on how accurate the level is built and how skillful you are in interpolating the location of the centered bubble (it's how walls get 1/2" out of plumb in the first place).

Ideally you'll use a plumb line.  This is just a piece of string or mason line with a weight at the bottom, hung so that it can swing freely.   Gravity does the rest and gives you a line that is truly vertical.  

Using a plumb line, and with the rifle level, I rotate the scope in the rings until the vertical cross hair is parallel to the plumb line. Then, I tighten the rings evenly, checking to ensure that the vertical cross hair remains parallel to the plumb line and the rifle remains level, while I snug and then torque the screws on the rings.  


5.  I verify that the line of sight is located directly over the centerline of the bore by looking into a mirror with a plumb line in front of it. The vertical cross hair should pass precisely through reflection of the center of the muzzle and the center of the scope objective lens, while the rifle is level.    

If you've got limited time and resources (no level, etc)  and/or a rifle action that is hard to level, this is the best shortcut method to getting a leveled rifle and scope.  You can hang a plumb line in front of the mirror and then use it to verify the crosshair is vertical when passing through the center of the muzzle and the center of the scope objective lens.  This also ensures the rifle is level, as what matters is the relationship of the line of sight to the centerline of the bore.  It's reliant on a calibrated eye ball, but properly and carefully done it will produce a very accurate result.  

Where this will not work is on a rifle with an offset scope, like the M1C and M1D Garand sniper rifles.  


6.  On a high quality scope the cross hairs should be perpendicular to each other and the reticle should be square with the elevation and windage adjustments.  Determining they are perpendicular can be done visually before installing the scope as it is usually pretty obvious looking though the scope if the horizontal and vertical cross hairs are not at a 90 degree angle to one another.  

However, you will need to do a box test at the range to verify that the reticle is aligned with the adjustments.  

A box test involves zeroing the rifle and then starting in the lower left hand corner of a large piece of paper.   Place a target dot in the corner and shoot a 5 shot group to confirm the zero.  Then crank in the windage adjustment needed to traverse the point of impact to the lower right hand corner.   There are three things you are looking for:

a) Verification that the adjustment distance is correct.   For example, if I added 20 MOA of right windage, I want to see 20.9"  of movement in the center of the group on the target at 100 yards.
b) Verification that the scope is level, and that the windage adjustment is square to the reticle. A straight line drawn between the center of the first group and the second group should be level.
c) Verification that there is no hysteresis in the windage adjustment (usually caused by back lash in the adjustment screw.  The second group should be nice and round like the first.  If you see horizontal stringing with the first couple shots landing short of the group center, it suggests backlash, where it takes a couple shots for the newly adjusted reticle to come to rest against the same screw face.   For me, this is the kiss of death for a scope and it'll be sent in for repair, returned or sold as the situation dictates.  I have no use for a scope with back lash in the adjustments.

You then dial in the vertical adjustment as needed to reach the top right hand corner of the target and shoot a third group.  You're looking for the same three items as you were in the second group: correct distance for the elevation adjustment used (I use 30 MOA on a B-27 target - more is better and will magnify any errors present); verification of a level scope and alignment of reticle and adjustments as evidenced by the 3rd group being directly above the 2nd group; and no indications of back lash in the adjustment.

Then return the windage adjustment to zero and shoot a 4th group.  This should be directly over the first group, with no indications of back lash in that direction.

Finally, return the elevation adjustment to zero and shoot a final group.  This should overlay the first group, with no drift in POI, and no indications of back lash.

Once you've shot all five 5 shot groups, you should have a square or rectangle with 90 degree angles between all the sides  If the resulting square or rectangle tilts to one side or the other, it indicates the elevation and windage adjustments are not square to the reticle. In that case, you'll want to rotate the scope the same number of degrees to correct the tilt and repeat the test.

A couple degrees of difference is unfortunately pretty normal even on a high end scope but you are much better off leveling to the adjustments than to the reticle.   If you don't correct for this, all your elevation adjustments will result in a slight windage change, and vice versa.  This will mean the vertical cross hair is a couple degrees off vertical when the rifle is level, however, in the real world, the local horizon will often not be level anyway, so you're not really losing much.   If use a scope level on the upper rear ring, you can still verify the rifle is level on long shots more effectively anyway.  

If you get a parallelogram where the angles are not 90 degrees, you've either got some cant in the rifle because you've improperly leveled the rifle ratline to the scope, or you've got internal scope adjustments that are not perpendicular to one another.   The former can be fixed but the latter cannot and will mean you are always going to get both a horizontal and vertical vector any time you make a windage or elevation adjustment.  That's another prime candidate for a return for repair, return or sale as the situation dictates.

Interesting to see people completely disregard the the fact that the scope does not need to be level with the rifle. Adjusting the rifle to a natural position for you and then leveling the reticle is actually a wise idea as your natural point of aim will then allow your scope to be level with a good stable shooting position where you rely on the least amount of muscle tension. You can then level a bubble level to be level with the reticle vs the rifle. This goes completely against what crap has been regurgitated by so many people four years but if you go shoot extended distances requiring dialing you will find that it works well and you are in a better shooting position that translates into less fatigue.

As long as the reticle itself is level then your scope adjustments will be correct as long as it tracks properly.

I love unintentionally adding wind to my firing solutions.

In what way does that happen if the reticle is being held level? Please tell me how the scope can defy physics in that case if the reticle is level and the turrets are tracking? There is a reason top rifle shooters don't worry about making the reticle level with rifle.

We've been over this so many times on snipers hide where I spend my time online and go by a different user name. Plenty of experts in the precision world have debated this one many times with old school and newer shooters.

Give this a read, but please understand what's being said, even if someone is an advocate of canting the rifle.

Canting effect on point of impact.

Now that you've read it, let's hit a few of the more subtle points.


1) If your rifle fits you in such a way that you have to twist it right or left to get the rifle level (i.e. both the center of the bore and the center of the optic are in the same vertical plane), there may be some merit to just letting the rifle sit naturally, in terms of building and maintaining a comfortable shooting position.  That's sounds like a good thing, however, there are some significant limitations to that approach.

2) You will still have a canting error even if the cant angle is perfectly consistent.  If you look at the graphic in the article, you'll notice the graph of the point of impacts at different ranges in a no wind condition is not a vertical line, but rather a parabola moving in the direction of the cant angle.  

That means that it will affect both the elevation and windage correction required at different ranges - even in a no wind condition.   For example, if you are canted to the left, you'll need to add increasing amounts of right windage even with no wind.  

You'll also have to add more elevation than would normally be the case with an un-canted rifle.  That plays hell with the suggested elevation input from a ballistic app, a whiz wheel or your spotter.  The farther the distance to the target, the greater the additional elevation needed.

Those limitations are no big deal if you are always shooting at known distances (i.e. a target shooter on a standard course of fire, such as a national match shooter with targets at 200, 300 and 600 yards.   The shooter just builds a range card with the required windage and elevation correction for a no wind condition at 200, 300 and 600 yards and then adds and subtracts the correction needed for the actual windage from that starting correction.   The availability of a couple sighter shots really helps as well.

It's even better for a shooter who shoots a match at a constant range, whether it's a small bore shooter at 100 yards or a high power shooter at 1000 yards.

3) Where it runs off the rails is in the field where the ranges are random.  

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Consequently, you'll see target shooters with some pretty extreme cant angles.  But they practice to maintain those cant angles very precisely, and they shoot at know distances, usually in matches that allow for a minimum number of sighters, or an unlimited number of sighters within an allowable time to make all the record shots.

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Personally, for my match rifle shooting, I use a 3 way adjustable stock so that the rifle achieves that natural point of aim with the rifle properly level.  It just makes life so much easier than dealing with a cant angle and the resulting corrections.  

For real world field shooting, where I may be engaging targets at different ranges, and where I'm using an off the rack stock that may want to tilt a bit to the left,  I'll sacrifice that perfect natural point of aim and rely on a bubble level to level the rifle.  

Why?  Because I don't want to figure out how much canting error is going to be present at 732 yards on one shot, 468 yards on the second shot and maybe 941 yards on the third shot.

That's especially true when the wind is blowing, and when I really need a high probability of a first round hit, rather than having the luxury of walking the rounds on target with 2-3 "sighter" shots.  

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In short, the context under which the shots are made matters, and it makes all the difference as to whether a canted rifle is a viable option or not.

For the shooting I do, I want a level rifle and I use a bubble level to ensure that - one that is level with the rifle, and the crosshairs.

^^^ That's a really good post.

Essentially you're mounting your scope offset from the centerline of the bore.

Even 5 degrees adds .1 mil of wind, making left/right winds have different values.

DakotaFAL, Issue one is the correct understanding of the issue at play, mounting a scope to the vertical plane of the rifle vs the vertical plane of the shooter. However, this is where individuals fall off track with the dissent regarding to allowing the rifle to cant naturally to the hold of the shooter. As long as that cant is taken account of and then the reticle is leveled in relation to the vertical axis of that natural point of aim, then there is no induced error that will be seen during shooting. While the rifle may be canted in this case, the scope itself is sitting on the level plane and as such no errors are induced. The scope gives ZERO fucks whether it is mounted level with the rifle or canted at an extreme angle of 45 degrees. As long as the rifle is then held so that the vertical axis is zeroed out there will be no errors down range. With this setup you can still run a bubble level as long as you mount it properly. Bubble levels should always be mounted to be level with the horizontal plane of a reticle. 

I understand that this goes completely against conventional wisdom for how this has been advocated for years and many people scream that this is heresy. However very few people are truly holding a rifle at a natural point of aim when the reticle is mounted level to the rifle. This in part induces muscle tension into your position which is not reliable at inevitably you will get fatigued when shooting positionally. If you venture past the realm of shooting from the comforts of a bench or prone then building a stable position which requires the least amount of muscle tension is key for success. At the end of the day this comes back to basic physics which you will never be able to defy regardless of how you mount your optic so long as the reticle is level to the horizontal axis when the shot breaks.