Help with scope set up...

[SilentStalker]

Ok, so I am trying to set my free M223 up on my flat top. I got it leveled in the mount according to the levels anyways but when I out it on the gun the scope seems canted to the left. Or, maybe I should say the crosshairs are canted. The scope seems level by eyesight as well but I suppose it could be off. Basically, I leveled the scope in the mount with a level sitting on top of the turrets, then tightened it all up, then moubted it on the gun. Once I did that I shouldered the gun and had someone put the level back on the turret to make sure I was holding the gun level. Holding the gun level and looking through the scope it looks like the crosshairs are canted left and can barely be seen which is odd because they seemed clear a fee months ago. I have also found that I seem to need to lift my head up when the rifle is shouldered to be able to see through the scope correctly. Obviously, I lose a good cheekweld when doing this. Does anyone know of some kind of riser I could put on the MOE stock? So, my question is do you guys think the scope is canted or ^^^do the crosshairs seem off because I am somehow angling my head weird to be able to see through the scope? I know it's hard to say without seeing it firsthand but I am out of ideas. I have messed with it for hours and cannot seem to get it spot on. However, I know for decent accuracy the scope needs to be set as correct as possible. Perhaps I should take it to a smith but it's brand new and I really don't want anyone monkeying with it too much.

 

[JPG19]

I have had the same issue with my M223 crosshairs although they canted to the right and have always been easy to see with a good cheek weld. I'm interested to see what others suggest.

 

[helotaxi]

The crosshairs might indeed be off. It isn't as uncommon as you would think. If the turrets on the scope are level the elevation and the windage adjustments will actually track correctly even if the crosshairs are canted. The problem is that your natural tendency will be to level the crosshairs when looking through the scope leading you to cant the rifle, which is bad when it comes to accurate, consistent shooting at any kind of range.

To confirm that the that crosshairs are indeed canted, place the rifle in a rest and place a level on the turret. Once the turret is leveled, use a plumb line to get a perfectly vertical reference in front of the rifle. This works easiest on a nice bare wall in the house. If the turrets are level and the vertical line in the crosshair isn't aligned with the plumb line, the crosshairs are canted.

The solution is to return the scope. That's it. It should be covered under warranty.

ETA: There is a cheek riser for the MOE and CTR stocks. I would address the mount first though since a cheek riser may interfere with the use of the charging handle.

 

[NeuseRvrRat]

so you put the scope in the rings first? i always mount the rings on the rifle first (without the top halves of the rings). put the rifle in a gun vise and stick a level across the flats on the bottom ring. adjust the rifle until it is level. then put the scope in the rings and put the top ring halves on and just get the screws started. adjust your eye relief as necessary. put the level across the elevation turret and level it up. tighten the screws and go shoot.

 

[Remllez]

OP,

Are you sure the gun itself is plumb before you mount/tighten the scope?

 

[helotaxi]

so you put the scope in the rings first? i always mount the rings on the rifle first (without the top halves of the rings). put the rifle in a gun vise and stick a level across the flats on the bottom ring. adjust the rifle until it is level. then put the scope in the rings and put the top ring halves on and just get the screws started. adjust your eye relief as necessary. put the level across the elevation turret and level it up. tighten the screws and go shoot.

I do it similarly, but I level the rail, scope base or a flat part of the rifle, not the rings. I don't trust the rings to be square.

 

[SilentStalker]

The scope is mounted in a Burris PEPR mount and is going on a flat top AR. If the scope is level and the rings are tightened and then the scope and mount is places on the rail and tightened down it should tighten down to the rail level, correct? This is assuming the rifle is level also. So then the only error could be me holding it wrong or the crosshairs canted. How ^^^do I tell if the rail is 100% straight? I mean if the rifle is level, the scope mount is level on the rifle, and the scope is level then the only thing it could be at that point IMO is that the crosshairs are canted, correct? Maybe that's why they sent me this scope free. Maybe they figure people that test this equipment should not have the best of the best stuff lol. Hmmmm....

 

[MCMXI]

it looks like the crosshairs are canted left

This is normal for a right handed shooter. If the reticle is perfectly aligned to the rifle, it will appear to be canted when you get behind the rifle because your head isn't vertical when your cheek is on the stock. A coworker who is a PALMA 1,000 yard national record holder cants his scopes 5° to 8° to the right (depending on rifle) so that the reticle is level when he's in position. Basically, he doesn't want to adjust his body position or rifle to the reticle, he adjusts the reticle to his natural body position when he's on the rifle.

 

[SilentStalker]

1858, that kind if makes sense. Thanks for that info. I may have to try that. I never really thought about doing that. I may take it to a smug though just to check my work. I think it's only like $30 for them to mount and sight it in but I could be wrong.

 

[MCMXI]

Ideally, we'd all shoulder or get behind our rifles so that we're in a completely natural and unforced position (repeatable) and then have someone rotate the scope (and move fore/aft for proper eye relief) so that the reticle is now aligned to a horizontal/vertical reference. Most of us don't naturally hold a rifle so that the stock and receiver are perfectly vertical, and with a comfortable and natural cheek weld our heads aren't vertical either.

 

[madcratebuilder]

Ideally, we'd all shoulder or get behind our rifles so that we're in a completely natural and unforced position (repeatable) and then have someone rotate the scope (and move fore/aft for proper eye relief) so that the reticle is now aligned to a horizontal/vertical reference. Most of us don't naturally hold a rifle so that the stock and receiver are perfectly vertical, and with a comfortable and natural cheek weld our heads aren't vertical either.

All this time I thought I was weird by canting my scopes in the mounts. It's just a few degrees and it seems I use more cant on AR's than bolt guns.

 

[helotaxi]

All this time I thought I was weird by canting my scopes in the mounts. It's just a few degrees and it seems I use more cant on AR's than bolt guns.

You realize that this is very problematic at long range, right? If the rifle is canted, the windage zero is only good at one range, just like the elevation. It also throws off the increments in the scope adjustments making dialing in elevation for range difficult if not impossible.

They make "anti-cant" devices for a reason.

 

[gotigers]

I am going to hijack, but kind of on topic:

Does everyone use a torgue driver for the mount screws? If so, what manufacturer, style, etc?

 

[helotaxi]

When I bother to torque them I just use an appropriate bit or socket on a Craftsman torque wrench.

 

[NeuseRvrRat]

You realize that this is very problematic at long range, right? If the rifle is canted, the windage zero is only good at one range, just like the elevation. It also throws off the increments in the scope adjustments making dialing in elevation for range difficult if not impossible.

They make "anti-cant" devices for a reason.

if your natural shooting position is to hold the rifle slightly canted and you mount the scope canted the opposite way by the same amount, then you'll be shooting with the scope level and you won't have the problems you describe.

 

[MCMXI]

if your natural shooting position is to hold the rifle slightly canted and you mount the scope canted the opposite way by the same amount, then you'll be shooting with the scope level and you won't have the problems you describe.

Exactly!! The important thing is that the muzzle moves vertically up/down as you adjust elevation, and horizontally left/right as you adjust windage. Forcing yourself to hold the rifle in an unnatural position to keep the reticle level isn't the best way to improve accuracy and precision.

 

[MCMXI]

Does everyone use a torgue driver for the mount screws? If so, what manufacturer, style, etc?

I mount all bases and rings using Wiha torque screwdrivers. I have 7.5 ~ 20 in-lb and 20 ~ 70 in-lb screwdrivers. I also lap all rings or one piece mounts if required.

 

[helotaxi]

Yes, you will still have problems, you might reduce the error with regard to adjustment graduation, but the windage problem hasn't changed a bit. Whenever the scope is not directly over the bore of the rifle, you have to solve an equation in two axes rather than only one to get a hit. If your target distance is different than your zero distance, you will have windage error. The amount of error is proportional to the difference between the zero range and the target range, the degree of cant (relative to the scope being directly over the bore) and the distance between the centerline of the bore and the centerline of the scope (sight height). I'd draw a diagram and explain it if you were nearby and I had a dry erase board handy.

 

[MCMXI]

helotaxi,
There are three possible scenarios and we'll assume that the shooter has zeroed the scope for 100 yards.

1. You mount the scope so that the reticle is aligned to the action/stock both horizontally and vertically. When shooting you hold the rifle so that the reticle is aligned to the target, therefore it follows that the receiver and stock are also aligned to the target. In this scenario it's highly unlikely that this will result in a natural shooting position but off a bench or a bipod shooting "free recoil" this isn't as big a problem compared to shooting in field positions. Vertical and horizontal adjustments are independent.

2. You mount the scope so that the reticle is aligned to the action/stock both horizontally and vertically. However, when shooting you hold the rifle in a natural shooting position so that the reticle is not aligned to the target and neither is the action/stock. This will result in holdover/holdoff errors as the range increases because as you adjust elevation you are also adjusting windage and vice versa. In other works, horizontal and vertical adjustments are not independent.

3. You mount the scope so that the reticle is aligned both horizontally and vertically to the target with the rifle held in a natural position i.e. most likely canted. If you've zereod the rifle at 100 yards, the reticle is centered over the bore ... it has to be. Clearly, the reticle is not centered in the tube in this scenario, however, further vertical or horizontal adjustments are independent.

 

[MCMXI]

I should add that the above assumes that the bore axis lies entirely in the vertical plane. This may be a huge assumption.

 

[rcmodel]

If you want it right?

Level the rifle action, then level the scope reticule on top of it with a small bubble level.

There is no possible way for a canted reticule to work right a longer ranges.

I don't care how you naturally hold the rifle.

The scope reticule has to be mounted on a vertical plane with the rifle or the bullet strike with get progressively further away from the aiming point the further away it gets.

rc

 

[helotaxi]

3. You mount the scope so that the reticle is aligned both horizontally and vertically to the target with the rifle held in a natural position i.e. most likely canted. If you've zereod the rifle at 100 yards, the reticle is centered over the bore ... it has to be. Clearly, the reticle is not centered in the tube in this scenario, however, further vertical or horizontal adjustments are independent.

With relation to the bore, with the rifle vertical, the scope is over the bore. As soon as you tilt the rifle, the scope is no longer directly over the bore with relation to the earth, which is the basis for gravity which is the "over" that matters since it is what affects the flight of the bullet. Try this one out. Cant the rifle 90 degrees. Rotate the scope 90 degrees to "compensate" and zero the scope. Shoot the rifle at any range other than what you zeroed it at and notice that you get an elevation error AND a windage error. In the case of an AR where the sights are 2.5" from the center of the bore, if you zeroed the rifle exactly at 100yds, the POI would shift laterally 2.5" at 200yds, 5" @ 300, etc. Essentially you would have to correct 2.5" for every 100yds beyond the original zero.

This is an extreme, but the same thing happens whenever you cant the rifle. It moves the sights laterally with relation to the bore and the planet. If you always cant the rifle, you can zero the cant out at some range, but it will induce a windage error at every other range. Rotating the scope has nothing to do with it, you can't rotate gravity. It isn't a matter of adjustments at this point, it's a matter of inducing a lateral component to the bullet flight with regard to the scope line of sight because the scope is no longer over the bore and you have to compensate with the zero.

 

[MCMXI]

Try this one out. Cant the rifle 90 degrees.

How about a realistic cant ... say 5°.

 

[rcmodel]

say 5°.

You will be off 5° at long range.

It's a fact of long range shooting that has been known for over 100+ years with champion shooters.

Creedmoor 1873 bubble-level front sight.
Used to prevent canting the gun.

http://www.pbase.com/halp/image/93149382

rc

 

[Remllez]

OP,
I'm pretty sure that unless your receiver is plumb and level (not canted at all) when you level your scope and tighten it down, every adjustment you make will be on a diagonal plane.

You will never be able to go dead straight up and down a vertical axis nor wll you ever be able to go dead level across a horizontal axis. The further away your target the larger the error will be. So unless your target is canted along the same axis as your scope you will never hit true vertical or true horizontal on your target.

Hope this helps......