Rifle Scopes Level Scope to earth or level scope to gun then level as a set to earth?

[DropinLead]

This seems a little unclear to me, leveling a scope is great but how do you translate that? More specifically the gun may not be true to the scope regardless of how you level things. The rail on my SPR is not level actually from front to back and it has a slightly high center for example.

So to properly ensure the scope is true to the gun and to the world, would you then:
A) Mount the scope level to the gun and then add anti cant level to set the gun and scope as a set parallel to the world with the plum line using the reticle's vertical line?
B) Level the gun and then set the scope and anti-cant level parallel to the world with the plum line using the reticle's vertical line and then mount the scope to the gun with disregard for specific scope to gun alignment?

My thought is level the scope to the gun and then level the whole set according to a plumb line? I use a Vortex Scope level for example. Seems I read lots of people lining up the scope parallel to a plumb line without regard for the gun like option A. Seems less room for error if you do option A. I am sure I am missing something. Maybe it makes no difference in the practical real world.

Thanks

 

[Lowlight]

I like to shoulder the rifle with my eyes closed, getting a nice natural position behind the rifle, making sure I am comfortable. Even do a few NPA Test by going through a couple of breathing cycles, then open my eyes and level the scope to gravity.

So when I open my eyes, regardless of where the rifle would fall if you put a level on it, I then move the scope so I have a perfect edge to edge sight picture eye relief wise. Then repeat the process and this time rotate the scope so the reticle is square to the fall of gravity with a plumb line or level.

This way you dont need an anti cant device because you are shouldering the rifle correctly in a natural way so you will always revert to that proper position. The scope is now level with the fall of gravity so that fixes that.

At that point you would only use a level to check to make sure you natural position is correct. If you constantly address the rifle that has a level on it, and you find your position is always off and you need to adjust to be level, then your system (rifle / scope) is not set up properly.

If your rifle has an adjustable butt plate you can use a level rifle with a level scope, then you can move the butt plate for comfort, but if you don't you have to move the scope so the rifle is naturally correct.

 

[KYpatriot]

Wait a second maybe I am misunderstanding something. LL are you saying the scope doesn't have to be level to the rifle, just to plumb? That wouldn't work with a canted base because even if the scope is level to plumb, if it is not also level to the rifle then when you dial elevation you would also be getting some windage out of your elevation. It has to be level to plumb and the rifle to make your elevation and windage corrections independent of each other.
In other words, option B in the OP.
Am I wrong?

 

[DropinLead]

Ahh, I do that to set cheek plate height and eye relief actually. I purchased the $12 e-book on the basics actually. I liked it btw. Thanks.

That instruction along with my NF optic perpetually looking like it is canted is what lead to me thinking about this. So in your post here, you are ensuring the scope is level to the earth(key point) and you are relying on a repeatable position when shouldering it. Not the rifle being level per say. That makes sense intuitively, and I like the idea of it, certainly it is easier, I like that, I may try it.

But.... what if your natural repeatable position with Mcmillian A4 stock with no Anshuts style adjustable butt plate, is actually with the rifle canted 4-5 degrees? Heck the natural pocket of the shoulder will all but ensures canting. Is that OK as long as it is repeatable? It seems rifle cant with the scope level may be an issue? That is the crux of the post topic actually.

Maybe it is not issue as long as it is repeatable and I am over thinking it. Perhaps rifle cant does not affect bullet trajectory relative to a level scope as you dial up elevation as long as the natural shouldering position with a cant is repeatable?

If rifle cant is not an issue (looking for confirmation) and all I really need to do is level the scope to a plumb line and use a repeatable position and throw out the anti cant device, or even better, set the anti cant device to my natural shouldering position as an aid, then my life just got a whole lot easier. I may be being too quantitative and need to be more qualitative about this.

 

[Lowlight]

Doesn't matter if the rifle has a slight cant in it, you can shoot with a canted rifle. if the scope is level the barrel is round and the degree off is not enough. You then moved it out of position less than a bullet diameter.

Not to mention the "odds" of you having at 4 to 5 degree cant are pretty slim, it's more like 2 degrees is normal. Everyone likes to exaggerate the canting effect to prove a point but i will submit if you are off that much and can't see it, you have a bigger problem.

People talk about "canting' the rifle and they mean the scope and barrel are together level to each other, not working separately. So think of a pendulum swinging away. By having a small angle in the rifle for comfort then offsetting the scope you don't get the same effect. Its no longer following that pendulum effect everyone tries to demonstrate. The canting errors happen when you have a level rifle and level scope and then move both on an angle. We are not doing that, you are using them independently.

The Tubb rifles have built in 5 and 10 degree offsets in them, where you purposely mount the scope at either the 5 degree position or 10 degree position. The key element is consistency, where canting in the context of a level is talking about an element of inconsistency.

If you address the rifle the same way and the scope is aligned to gravity, you are consistent, and there is no problem. if you level the scope to the rifle and then naturally cant the system together you are inconsistent and working against the zero, instead of with it.

 

[DropinLead]

Wow OK, sure wish every post on the whole internet about mounting scopes just said what you just said. Using levels just frustrates and in the end I know it is all not level anyhow. I used 5 levels, parallel plates and feeler gauges with variance of just .0005 between the bottom of my NF scope and the rail. I promise there has never been a more precise level than may gun and scope, in addition not one of the 5 level bubbles moved even a hundredth of an inch, 8 times leveling it and 16 hours of effort and yet... it was not level. The whole "how do you know the gun is level" is where I wound up. Level the scope to a gun where level surfaces are off and the whole thing is off. My gun is not level despite levels telling me it is, surfaces are not square enough.

Who cares if the gun is level, natural repeatable hold and then level reticle to the world. Perfect, easy. Thanks.

 

[Aceshigh109]

Make this one a sticky ? I had the same situation as Dropin.. leveled the scope in a Spuhr mount on my Ai using the little tapered tool, ok good to go, near as damn it, the scope is now level with the base, etc etc... it's not until I adjusted the butt plate to give me a repeatable natural position that allowed the rifle to be upright that the reticle actually was vertical when in position. With the butt plate set straight up and the scope perfectly leveled in the mount... it was off...

This is the best/simplest thread I've read on leveling ..

 

[Oleshep]

Correct me if I am wrong but if you are going to use hold overs on the 6oclock tine of the scope it needs to be perpendictual to the bore or you are going to be off on windage as you go out to longer yardages? If you are dialing in the eleveation I would think the erector assemply would also show devaition on windage as you dialed in more elev?

 

[dcjs]

The situations when

a) the rifle with a scope that is mounted level above the bore is canted together with the rifle
b) the scope is mounted level but not centered above the bore

produce partially different errors, but they both do produce errors (when shooting at/adjusting for different ranges). Since the error is comparatively small in the second case, it's not worth fretting about having the scope level relative to the rifle up to the last degree, keeping the scope square with gravity is much more important.

 

[Lowlight]

There is no rule that says the scope has to be a specific way on top,

There are variations in the rifle, there are imperfections in the barrels, (they are not always aligned 12 to 6 O Clock) there are a host of things that can be off which we never see. This is why certain things don't necessarily work the same for everyone. Also look at rifles like the M1D, the scope is mounted to the side, not directly over the top. The TUBB2000 & Spec Tac Lar too. So picture the M1D and shrink the offset to less than the width of the bullet. Is that small variation gonna matter compared to attempting an unnatural position where the body and mind will self adjust, vs being consistent. Consistency is king, if the rifle is being addressed in an "unnatural" way our mind will fight that, where naturally addressing it is repeatable, we can focus on the firing task. While the distance is not as great Olympic and Service Rifle Shooters will also shoot at an angle. The adjustability of their rifles is a key element to their personal accuracy. Why we are not insisting on an adjustable buttplate is beyond me, but I opt for it when I can for sure.

Page 1 of David Tubb's DTR Scope Instructions State:

Here’s how to get your DTR on target quickly...
Level your DTR scope to your natural position. The Horizontal stadia lines will indicate the scope has been leveled.

Now his scope is not level to begin with, so using a level is required with it, but he still wants you in a position you can naturally get into. The level is a training tool, a device not to shoot by, but to educate the shooter regarding their position. Constantly chasing level because your body wants to be pointed one way and the level tells you point the other should be a clue. Set the rifle up to you and then adjust the scope to level.

 

[DropinLead]

Correct me if I am wrong but if you are going to use hold overs on the 6oclock tine of the scope it needs to be perpendictual to the bore or you are going to be off on windage as you go out to longer yardages? If you are dialing in the eleveation I would think the erector assemply would also show devaition on windage as you dialed in more elev?

The key points are quoted below from LL, it is the part that I was missing. Cant is fine in certain conditions that are met when you mount the way LL outlined.

Doesn't matter if the rifle has a slight cant in it, you can shoot with a canted rifle....

The canting errors happen when you have a level rifle and level scope and then move both on an angle. We are not doing that, you are using them independently.

If you address the rifle the same way and the scope is aligned to gravity, you are consistent, and there is no problem. if you level the scope to the rifle and then naturally cant the system together you are inconsistent and working against the zero, instead of with it.

This is really simple, seems posts make it more difficult than it is, like I was doing btw...

 

[Lowlight]

Somewhere there is an image of the offset, everyone thinks it's some crazy degree of misalignment when it's not. It's tiny.

Like I said you are not canting the rifle huge, it's probably only a degree or two and then rotating the scope puts you back in like and the offset is less than the width of the bullet.

People have it in their head it's big, that only works when you move both together away from the actual zero. Then you get the canting effect every crows about. In that case you are swinging the scope and rifle away in opposite directions in this case you are not.

It is still over the bore, just set up to one side, if it makes you nervous, zero .1 (.25) to the left or right of center depending on your hold. It will stay there, just like the M1D.

Hold offs work the same, you are not raising the barrel at an angle, and your erector is not traveling at one, its still lined up with the fall of gravity and you lift with that same fall.

 

[Oleshep]

Okay I understand what you guys are saying now. Thanks for the clarification..

 

[dcjs]

Maybe I should have rephrased case b) to "having the scope offset sideways relative to the bore", because that is what counts (and it is a result of the canted mount/level scope situation). The resulting error is small when the angle and scope above bore height are small, but it is an angular error so it gets bigger with distance.

Example: 10° of cant and a mounting height of 70mm (both is a lot and used to illustrate the point only) will result in an offset of 12 mm. If the rifle is zeroed at 100 m, that offset will result in an angular error in the horizontal plane of 0.12 mrad beyond 100 m, that is 12mm at 200 m and 108 mm at 1000 m. Still not much (about a 0.1 mrad click). The funny thing is that if the zero was off to the side by 12 mm to start with, the error will indeed be constant (12 mm at all distances) because the line of sight and the bore remain parallel in the vertical plane. So even for extreme cases, the error is usually less than the "resolution" of the click adjustment, so you're indeed way better off worrying about the consistency of getting behind the gun.

 

[CEL317]

... if the scope is level the barrel is round and the degree off is not enough. You then moved it out of position less than a bullet diameter. ...

Lowlight, are you saying that you can only put a slight cant in the rifle and mount the scope to gravity if the scope is level (parallel) to the barrel? Meaning, you cannot cant the rifle with the scope mounted on a 20 MOA base?

 

[Lowlight]

Lowlight, are you saying that you can only put a slight cant in the rifle and mount the scope to gravity if the scope is level (parallel) to the barrel? Meaning, you cannot cant the rifle with the scope mounted on a 20 MOA base?

I didn't say any of that... in fact I have no idea what you are trying to say, I said nothing about your base being canted for elevation in the scope. Has nothing to do with it

 

[CEL317]

I didn't say any of that... in fact I have no idea what you are trying to say, I said nothing about your base being canted for elevation in the scope. Has nothing to do with it

I must have misunderstood and I wasn't trying to put words in your mouth. I was simply attempting to clarify is all. Can you mount the scope to gravity with the rifle canted and have a 20 MOA base in the middle? Or can you only do that without the base?

 

[Lowlight]

Yes one thing has nothing to do with the other.

 

[GUNNER10]

great info lowlight, never really thought about it that way but it makes sense, good stuff

 

[DropinLead]

Lowlight, are you saying that you can only put a slight cant in the rifle and mount the scope to gravity if the scope is level (parallel) to the barrel? Meaning, you cannot cant the rifle with the scope mounted on a 20 MOA base?

Canting as in horizontal deviation relative to a level horizon. The 20MOA base you refer to is vertical and is elevation not deviation from a rolling axis.

Thanks much, off to re-do the scope the the LAST DAMN TIME.

 

[pawprint2]

I have read a very interesting article over on Accurateshooter.com, David Tubb et al, who know more than I had this to say:
Effects of Rifle Canting at Long Range — David Tubb Explains

Eleven-Time NRA National High Power Champion David Tubb knows a bit about long-range shooting. One of the key factors in long-range accuracy is making sure that the tilt/cant of your rifle does not change throughout your shot string. In the clip below, the first in McMillan’s Master Class Video series, David Tubb explains the importance of keeping your rifle level. He explains that, at 1000 yards, your Point of Impact can change dramatically by canting the rifle either right or left. David states that, when shooting at 1000 yards, if your rifle is level and your shot is centered-up on a 72″ (six-foot) square target, you can actually put your next shot OFF PAPER by canting your rifle. That means you can move Point of Impact (POI) three feet or more, just by canting your rifle!

Bryan Litz confirms Tubb’s observation. Bryan tells us that, as a general rule of thumb (for common cartridges), a 1° cant will produce five (5) inches of lateral displacement at 1000 yards. Thus, if you cant your rifle just 8°, the POI would move 40″ from the center of the target, putting the shot off the edge of a 72″-wide target.
------I believe they are talking about canting as a change from the original "zero". Anyone have any thoughts?

 

[TheGonz]

Just get a surgeon action with broached rail and a Spuhr mount with wedge leveler and be done with it. Tada!

 

[TheGonz]

Bryan Litz confirms Tubb’s observation. Bryan tells us that, as a general rule of thumb (for common cartridges), a 1° cant will produce five (5) inches of lateral displacement at 1000 yards. Thus, if you cant your rifle just 8°, the POI would move 40″ from the center of the target, putting the shot off the edge of a 72″-wide target.
------I believe they are talking about canting as a change from the original "zero". Anyone have any thoughts?

That is why I align my reticle to the rifle, not to the world. I shoot level to the world, two different things. The downside is you have to assume they machined the action and threaded the barrel exact and working in manufacturing for a while I can tell you that not every action is perfect, but that's why God invented CMMs

 

[springer01]

If you mount your scope with the feeler gauge type method the scope/reticle should be center/level with the rifle. As long as the base is true.

 

[Lowlight]

I have read a very interesting article over on Accurateshooter.com, David Tubb et al, who know more than I had this to say:
Effects of Rifle Canting at Long Range — David Tubb Explains

Eleven-Time NRA National High Power Champion David Tubb knows a bit about long-range shooting. One of the key factors in long-range accuracy is making sure that the tilt/cant of your rifle does not change throughout your shot string. In the clip below, the first in McMillan’s Master Class Video series, David Tubb explains the importance of keeping your rifle level. He explains that, at 1000 yards, your Point of Impact can change dramatically by canting the rifle either right or left. David states that, when shooting at 1000 yards, if your rifle is level and your shot is centered-up on a 72″ (six-foot) square target, you can actually put your next shot OFF PAPER by canting your rifle. That means you can move Point of Impact (POI) three feet or more, just by canting your rifle!

Bryan Litz confirms Tubb’s observation. Bryan tells us that, as a general rule of thumb (for common cartridges), a 1° cant will produce five (5) inches of lateral displacement at 1000 yards. Thus, if you cant your rifle just 8°, the POI would move 40″ from the center of the target, putting the shot off the edge of a 72″-wide target.
------I believe they are talking about canting as a change from the original "zero". Anyone have any thoughts?

And all those guys who preach canting effects, even at Accurate Shooter are selling you something related to canting.

Yes if you move the rifle and scope together to cant you cause issues, but we are not doing that, we are not swinging the scope opposite of the barrel. That is the key.

Apples and Oranges... a level rifle with a level scope canted is a problem, we are not advocating that... nor are we selling you a product either.

 

[bribri]

Tag for later

 

[MarineMD]

I was watching Best of the West and Lloyd Hill suggested putting a slight can't in your scope related to the rifle to make up for bullet spin-drift when greater than 500 yards.

 

[springer01]

LL if you level your scope like you are saying how do you assure it stays level when you tighten the rings down? I have been using the feeler gauge method for several years, but this has me second guessing my methods. I have never had a level on my rifle while in shooting position so not sure if I am canted but my reticle always looks level when shooting.

 

[WVshooter]

Interesting points have been made. I had always assumed you wanted everything level. The gun level, the scope leveled to the gun the vertical stadia bisecting the barrel. I've used the feeler gauge method since reading about it on here and it works great for me. I'm still amazed sometimes that it is even possible to send a bullet over a thousand yards and hit a relatively small target consistently.
It makes sense though that you would want a natural feeling position with the scope leveled to gravity to be truly consistent and not have to force a shooting position just to get everything level. I guess it is easy to picture something that is way more extreme than reality when visualizing the relationship of the scope to the bore and a degree or two of cant relative to the two centerlines.

 

[Lowlight]

LL if you level your scope like you are saying how do you assure it stays level when you tighten the rings down? I have been using the feeler gauge method for several years, but this has me second guessing my methods. I have never had a level on my rifle while in shooting position so not sure if I am canted but my reticle always looks level when shooting.

it's a secret, you have to unlock the code

 

[MarineMD]

I was watching Best of the West and Lloyd Hill suggested putting a slight can't in your scope related to the rifle to make up for bullet spin-drift when greater than 500 yards.

 

[Lowlight]

That is what David Tubb advocated before he produced his own reticle and built the SD into it. It was like 6 degrees I think, you used your level to make sure you were consistent with the built in cant

 

[nick_charles]

Tag for reference

 

[springer01]

it's a secret, you have to unlock the code

The only way I can see to do it would be to put a level on your scope and see where the bubble is when you get it set where you need it. Torque the rings keeping the bubble in the same spot as you tighten them? Am I even close?

 

[Cproflow]

I'm guessing it would be easier to get yourself set up naturally, get the reticle matching a plumb line/level...and then have someone else tighten down the rings.

 

[steves1911]

I like to shoulder the rifle with my eyes closed, getting a nice natural position behind the rifle, making sure I am comfortable. Even do a few NPA Test by going through a couple of breathing cycles, then open my eyes and level the scope to gravity.

So when I open my eyes, regardless of where the rifle would fall if you put a level on it, I then move the scope so I have a perfect edge to edge sight picture eye relief wise. Then repeat the process and this time rotate the scope so the reticle is square to the fall of gravity with a plumb line or level.

This way you dont need an anti cant device because you are shouldering the rifle correctly in a natural way so you will always revert to that proper position. The scope is now level with the fall of gravity so that fixes that.

At that point you would only use a level to check to make sure you natural position is correct. If you constantly address the rifle that has a level on it, and you find your position is always off and you need to adjust to be level, then your system (rifle / scope) is not set up properly.

If your rifle has an adjustable butt plate you can use a level rifle with a level scope, then you can move the butt plate for comfort, but if you don't you have to move the scope so the rifle is naturally correct.

I've used this method on my long guns and my sons newly acquired AAC and it has worked wonders. A great piece of advice, Thanks Frank!

 

[DropinLead]

The only way I can see to do it would be to put a level on your scope and see where the bubble is when you get it set where you need it. Torque the rings keeping the bubble in the same spot as you tighten them? Am I even close?

That is exactly what I did tonight using vortex scope level.

Despite crazy detail to leveling the base, the gun, the scope on top and bottom, using parallel plates and feeler gauges, the reticle always seemed canted counter clockwise once i was done and at the range where inwould level my anti cant level. 11:58 describe it as.

If it were not for the anti cant I would have lined the reticle verticals and never would have known the scope level was off. All my work was telling me it was as level as hell.

Well tonight I set a vertical plumb and LL says and sure as hell reticle was NOT level. I reedit it, all is good now. Actually for giggles I checked... I actually leveled the gun first since i wanted to compare apples to apples with the technique.

Something interisting happend, technically the gun and scope are STILL level to each other still but to the left of the center bubble level lines. Still between the two centering level lines, just shifted to the left as opposed to the bubble being centered. Both gun and scope shifted the same amount. Whole thing took 30minutes, he'll it took that long just to tighten with decremental feeler gauges and the whole thing of watching for bubble shift and managing 5 levels took hours and NEVER yielded a level setup.

So now the gun and scope are level to each other but the difference is the reticle is now also level, something in the leveling process was not level and me shimming to make it level was clearly the problem. My guess is the scope rail is not true. me shimming the gun to get that level was infact making it unlevel. Guaranteed this happens to lots of guns. I suspect many people do not notice or care. Levels say it is level!

Btw, I added the canting level to the scope, I may have a bystander set it to my natural shooting position and redo the scope, then set levelmtomlevel. Need two people for that, in this way I can have the gun in natural position and use a level to ensure I always get it there. Using an anti cant level as a natural cant level basically, level would be my natural position with scope level in other words.

What LL layed out here just layed out here saved me from massive frustration. Frankly it was easier and yielded better results. Confidence is restored as i watched the reticle drop straight vertical through 30 elevation clicks.

I was dead convinced I got a bad scope from NF till LL layed the truth on me. Seriously, thanks for taking the time!

WTH is up with all the crappy "how to mount scopes" posts that basically tell you how to properly, improperly mount a scope.

 

[Sportin Wood]

I like to shoulder the rifle with my eyes closed, getting a nice natural position behind the rifle, making sure I am comfortable. Even go through a couple of breathing cycles, then open my eyes and... realize I'm playing in my backyard with a stick with a toilet paper tube on it

There yuou go.. fixed it for ya Franky

 

[pawprint2]

That is what David Tubb advocated before he produced his own reticle and built the SD into it. It was like 6 degrees I think, you used your level to make sure you were consistent with the built in cant

I hope that David Tubb has learned something new, something he feels is a better way, rather than selling his good name for a few dollars. I'm just saying...

 

[KYpatriot]

Thanks LL - I get it, if there is any rifle to scope cant all it does is create a small offset as long as the reticle is aligned to plumb. Unless the rifle to scope can't was a crazy angle the offset is very small and lost in the noise.

 

[Papagallos]

I like to shoulder the rifle with my eyes closed, getting a nice natural position behind the rifle, making sure I am comfortable. Even do a few NPA Test by going through a couple of breathing cycles, then open my eyes and level the scope to gravity.

So when I open my eyes, regardless of where the rifle would fall if you put a level on it, I then move the scope so I have a perfect edge to edge sight picture eye relief wise. Then repeat the process and this time rotate the scope so the reticle is square to the fall of gravity with a plumb line or level.

This way you dont need an anti cant device because you are shouldering the rifle correctly in a natural way so you will always revert to that proper position. The scope is now level with the fall of gravity so that fixes that.

At that point you would only use a level to check to make sure you natural position is correct. If you constantly address the rifle that has a level on it, and you find your position is always off and you need to adjust to be level, then your system (rifle / scope) is not set up properly.

If your rifle has an adjustable butt plate you can use a level rifle with a level scope, then you can move the butt plate for comfort, but if you don't you have to move the scope so the rifle is naturally correct.

What position is best to use while leveling a scope to the fall of gravity? Bench? Prone? Or is this irrelevant? I apologize ahead of time for the stupid question.

 

[Pinecone]

I have read a very interesting article over on Accurateshooter.com, David Tubb et al, who know more than I had this to say:
Effects of Rifle Canting at Long Range — David Tubb Explains

Eleven-Time NRA National High Power Champion David Tubb knows a bit about long-range shooting. One of the key factors in long-range accuracy is making sure that the tilt/cant of your rifle does not change throughout your shot string. In the clip below, the first in McMillan’s Master Class Video series, David Tubb explains the importance of keeping your rifle level. He explains that, at 1000 yards, your Point of Impact can change dramatically by canting the rifle either right or left. David states that, when shooting at 1000 yards, if your rifle is level and your shot is centered-up on a 72″ (six-foot) square target, you can actually put your next shot OFF PAPER by canting your rifle. That means you can move Point of Impact (POI) three feet or more, just by canting your rifle!

Bryan Litz confirms Tubb’s observation. Bryan tells us that, as a general rule of thumb (for common cartridges), a 1° cant will produce five (5) inches of lateral displacement at 1000 yards. Thus, if you cant your rifle just 8°, the POI would move 40″ from the center of the target, putting the shot off the edge of a 72″-wide target.
------I believe they are talking about canting as a change from the original "zero". Anyone have any thoughts?

He is talking about zeroing the rifle, THEN canting the entire thing for the next shot. Not zeroing the rifle at a consistent cant.

Canting after zero makes a portion of the elevation setting for the range into a lateral change in sight picture versus POI.

 

[jbell]

What position is best to use while leveling a scope to the fall of gravity? Bench? Prone? Or is this irrelevant? I apologize ahead of time for the stupid question.

You do it in your dominate position for that rifle. If you shoot offhand unsupported then do it in that position, prone with bipod and bag then that way ECT...

I think everyone is over thinking this a bit too much. Follow what Frank said or whatever method you are comfortable with. But if you get your NPOA and the ret is canted then you should adjust it until it is. A plumb line at a moderate distance 100yds or so should be your reference as the horizon is not a good reference. After that if your scope tracks perfectly straight up when in a position built around your NPOA then you are done.

As far as a anticant device, they have their place in precision shooting as well. There are times when your targets background will be deceving and make you think you are holding the rifle canted when you actually are not. If the anticant device is correctly installed on your scope/rifle then it is a better reference than the horizion. I install mine level to the ret and the plumb line I described earlier.

But then again I dont hit everything I shoot at so I may be full of shit...

 

[bm11]

Frank is completely right. As long as the scope is level to the ground when you are shooting it, it doesn't matter what the rifle is doing underneath it.

That said, there is more than one way to skin a cat and because of OCD issues I tend to want the rifle level to the ground and the scope level to the rifle, level to the ground, with an anti cant on just for reference (leveled to the scope, rifle, and ground.) My rifles are all fully adjustable so I spend the time setting them up so that my NPA also coincides with a level rifle.

 

[mdesign]

Very true...set up your rifle to NPA and plumb in your scope. My NPA (and natural cant in the way I hold my rifle) happens to be very close to plump for my scope.

 

[nfoley]

Exellent info, have used lowlight's advice for a while after asking him the same question.