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Scope reticle leveling / rifle cant

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/10/2008 at 09:40
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YippeeI know somewheres I saw a thread/video on rifle canting(rotational drift) and how to correct for level a  mounted scope’s reticle. I’m unable to find it now..Something like drawing a target plumb line and making sure its perfectly plumb with a 4’ mason level. Then take aim at 50 or 100 yds(I’m unsure what’s most efficient), making sure to keep your elevation reticle is perfectly parallel to the target plumb line you just drew on the target. Fire the shot,(assuming it’s a ‘good’ shot), if it ends up right or left of the plumb line, you know your rifle is canted and have to adjust . If its dead on center or very very close then no adjustment necessary. If POI is off,  rotating scope to the side of the POI. Now, I’m a little confused on how much rotation is needed but I assume it’s in 1/16” or 1/8 or ¼ “ increments something like this – sort of trial and error with follow-up shots. CAN SOMEONE PLEASE GIVE ME THE LINK TO THIS VIDEO OR let me know how close I am in my description. thanks (ps. I prefer this method over any ‘gadget’ that can be bought) (pps. I know there is a way to level your scope using a line level on the receiver, then lay the level on the top of the scope but I’m not sure I trust this method. . anyway there is little horizontal ‘flat’ area on my receiver so that I can make sure the rifle is level) thanks .. pps. if this is a little long-winded, IT IS..  out.Excellent

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/10/2008 at 10:07
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Sorry bro, this does not make sense. It could be shooting left or right because the scope is not zeroed. Maybe if you cranked the dial all the way down and then zeroed the rifle at the bottom of the target and then cranked the elevation all the way up again. At this point keep your elevation line plumb (you would need to have a few on your target to find one to plumb up to. Then fire a shot. Did it move left or right?
I do also think that rifle cant will not show up at such short distances. I think you need to go out to 800yds+
 
Then the variables, was it the scope with poor tracking? Was it the shooter, rifle?
Sorry cannot help with video (Also took me a while to get to the answer)
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/10/2008 at 10:26
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A.)  exactly my point. We are talking fractions of an inch BUT, if, say, you are shooting over long distance it begins to make a difference, if the scope reticle is out of plumb with the bore axis you can enhance the cant and thus POI will drift further.

B.)  If one could correct this so the reticle is perfectly ‘squared’ to the bore axis, wouldn’t yo feel better making long distance shot?

C.)  There are different methods to correcting this , the one I explained above is a real method, I just cant find the article/thread/video or whatever..

D.)  zeroing and adjusting for a plumb reticle I would assume go hand-in-hand, but in this case if one only eyeballed the reticle when mounting one would want to do the above operation.

E.)   since I posted my question, I found this nifty site..Yippee out.

http://www.riflescopelevel.com/vertical_retical_instrument.html
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/10/2008 at 10:58
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Level your scope is a small level, a gun rest, and a large level - or just use feeler gauges and don't worry about the levels.

What you suggest will not work.  If you find a video recommending such a procedure, let me know so I can put that person in the "don't know sqaut about precision rifle" category.

In your leveling process, no rounds should be fired.  hell, it's hard enough to hit the target when you know the scope is leveled and zeroed - making a process that does all at once: no chance!


Don 't buy the $100 gimic!  Invest in a good level or a set of feeler gauges.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/10/2008 at 11:27
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Hey Charlie
 
Not too long ago there was this thread http://www.opticstalk.com/forum_posts.asp?TID=10099
 
That was my rifle and since then I have gotten a Wheeler Level-Level-Level set www.wheelerengineering.com .  If you can get it to work on your rifle then it will work.  So far it works on both my Beretta Mato's by inserting in the action and my Sako action by placing on the built in dovetail scope base on the rifle.
 
I also used it on a Browning BBR and Remington VLS but haven't figured out how to use it on my Steyr.
 
What I have started doing is putting the gun in the vise, leveling the action ( by whatever flat surface I can find on the gun ), then leveling the scope by rotating and then setting the scope mounted level.  So all three bubbles are leveled.
 
Then I take it to the range, shoot to check zero, click 30 clicks up, shoot and then check to see if the POI is vertically aligned with the lower POI.  I have begun to like the scope mounted bubble a lot because at least it will keep you from canting and give you a repeatable vertical hold at the longer distances.
 
That is a nifty website you found.  I will save it and give some thought to it.  Might be the answer, who knows?


Edited by sakomato - August/31/2008 at 22:15
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/10/2008 at 11:42
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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/10/2008 at 12:10
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to reply rancid coolaid/8shots::

its simple, if your rifle cants it will show up on target . You CAN zero a rifle with a reticle out of plumb unknowingly. if your rifle is being shot from front and rear rests. And, if you want to check for it, you plumb a target line and fire shots (from rests of course) with your elevation reticle parallel to a known true plumb line.

I know the video exists, and I will definitely let you know if I find it again.

 

OR ,

of course, you can level the reticle right from start which I did not do and just eyeballed it – at this point in my case I have trouble since its hard to get a horizontal level bubble off a spot on my rifle . I will just have to figure it out I guess…

 

sakomato:

yes, exactly where I was coming from. I missed these threads, good info.  I like the wheeler leveling system, maybe it will work for me and will have to check into it more.  thanks.

wish I could use the feeler gauge system, might not work for me..  nice AI and Nightforce rig anyway…

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/10/2008 at 17:51
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I would guess that the vast majority of casual shooters have scopes that are not level.  Almost everyone cants the rifle.  It is entirely possible to be dead-nutz zeroed at a specific range and have a canted reticule.  I know, I've done it!

Leveling the scope only makes the reticule level when the gun is level.  Most people cant the rifle when they shoot.  This is not a problem so long as your distances are not extreme, your changes in dope are not frequent, and you always do everything exactly the same.

If you really want good long-range precision and accuracy, you will need to mount the scope properly, put a level on the action (so that the rifle/scope are level when you squeeze the trigger) and know from experience where bullets land at range. 


I've seen MANY shooters zero at 100 yards and think they can dial in some published "come-up" and be dead on at 600 yards - it usually doesn't work that way.


The level-level-level thing seems like a good idea, never used it, but do something very similar.

Good luck.  Shoot straight.  And don't miss.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/10/2008 at 18:23
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Originally posted by Charlie-bolted Charlie-bolted wrote:

YippeeI know somewheres I saw a thread/video on rifle canting(rotational drift) and how to correct for level a  mounted scope’s reticle. I’m unable to find it now..Something like drawing a target plumb line and making sure its perfectly plumb with a 4’ mason level. Then take aim at 50 or 100 yds(I’m unsure what’s most efficient), making sure to keep your elevation reticle is perfectly parallel to the target plumb line you just drew on the target. Fire the shot,(assuming it’s a ‘good’ shot), if it ends up right or left of the plumb line, you know your rifle is canted and have to adjust . If its dead on center or very very close then no adjustment necessary. If POI is off,  rotating scope to the side of the POI. Now, I’m a little confused on how much rotation is needed but I assume it’s in 1/16” or 1/8 or ¼ “ increments something like this – sort of trial and error with follow-up shots. CAN SOMEONE PLEASE GIVE ME THE LINK TO THIS VIDEO OR let me know how close I am in my description. thanks (ps. I prefer this method over any ‘gadget’ that can be bought) (pps. I know there is a way to level your scope using a line level on the receiver, then lay the level on the top of the scope but I’m not sure I trust this method. . anyway there is little horizontal ‘flat’ area on my receiver so that I can make sure the rifle is level) thanks .. pps. if this is a little long-winded, IT IS..  out.Excellent

 
I'm pretty confused, too.   Stare     Go to New York City. Set up a bench on 34th St. and aim your rifle and scope at the Empire State Building.  Align the vertical crosshair along the edge of the Empire State Building---THAT ought to be real straight!  Bucky
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/11/2008 at 03:56
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Charlie-bolted, my point is that say you zero your rifle at say 100yds with a canted scope.  You then draw a parallel line with a level or plumb line through this bullet hole. If you then rotate your reticule onto this line, you will simply be rotating the scope and POI on the bullet hole as the center point. Should you fire a second bullet, it should impact on the first bullet hole. (I can theoretically lie the rifle on its side and aim at the bull and I will still hit it at 100yds)If you however move the reticule up or down, you could find the new bullet hole left or right of the vertical if the scope was canted to begin with.
 
I think what this  test will do is test if your reticule is centered in the scope housing. Should you zero the scope with say a deliberately canted reticule, and you then level it and fire a second shot and it impacts left or right, it means your reticule is not in the center of its setting. This is why one first centers the reticule by rotating it on a plumb line before mounting it. When you rotate a scope on a plumb line it should remain on the plumb line if you rotate it 180 deg.
 
 The reason a canted scope effects point of impact is only when you adjust the reticule up or down. Should the reticule stay put, but the rifle itself is not canted, it will not effect the point of impact at any distance. In other words if you simply aimed higher to allow for bullet drop. It therefore makes sense that to test for scope cant, you have to move the reticule up and down by elevation knob to test if it stays on the plumb line.
Now a canted RIFLE is another matter. By shooting a canted rifle the arc of the bullet is effected by gravity. So the bullet will start its normal arc in the direction of the cant, and then as gravity takes hold, the bullet will drop, giving a corkscrew downwards arc.


Edited by 8shots - April/11/2008 at 04:12
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/11/2008 at 08:25
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there are 10 kinds of people in the world those that understand binary and those that don't.
unless your shooting 600+ yds. it won't matter, the probablity that you will hold the gun the same way everytime is higher than your being able to detect the gun off cant-- unless you use a bubble or electronic cant device. A lot of "practical" shooting in the field has the shooter looking for a "horizon" before approaching the scope, then matching the horizon with reticle as "one comes up on the shot" . If one doesn't lhave time for this the target is close enough you don't need it anyway. If your using a gun good enough to shoot the difference in cant, then probably the loads aren't and it still doesn't matter. If both are up to it your probably shooting a rail gun in a benchrest match or hanging to long on the shot.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/11/2008 at 20:44
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Well I realize these people want to sell their product but here is what their literature says (hope it's readable)
 
 
It looks like the chart on the left will be pretty much unreadable.  What it shows is the amount of additional drop caused by canting.  For example at a distance where the normal bullet drop is approx 32" (180 gr TTSX @ 3050 fps @ approx 450 yards) the additional bullet drop from a 6 degree cant will be 3.5".  Not terribly significant, but that is additional bullet drop and not the sideways movement.
 
Besides I think it looks kinda cool on the scope.  
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/12/2008 at 09:23
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most of Tubbs guns are canted, he doesn't seem to have the problem.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/12/2008 at 11:48
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Hey Dale, to say David Tubbs cants his rifle might be considered and understatement!  Shocked
 
 
Of course he shoots a lot and compensates in all sorts of ways for cant.  I think that particular rifle is set up so he rests his chin top of the stock.  Loco
 
Here another discussion and where I got the picture
 
 
I'm in the camp that if I understand and can minimize cant, scope rotation, bore alignment, etc.  then I am better off.  Besides I need to do something with my spare time.  Big%20Grin
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/15/2008 at 03:23
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Charlie-bolted, see this excellent thread posted by Sakomato. It is as we all stated. You will only see if the scope is canted by dialling up or down.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/15/2008 at 07:59
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I re-read the article. I then cut out a circle and drew a reticule on it giving me a "scope". I then zeroed my "scope". I then drew the t-line as suggested. With a deliberately canted "scope" I dialled up, meaning the crosshair moves down and to the right of perpendicular. I know aim at the same point as my first "bullet hole", still with the same cant on the "scope". The new impact point shows to the right of the perpendicular. I then align the scope with the horizontal as stated by the article. The new Point of Impact shows back exactly on the perpendicular (not left or right). All I have done is effectively canted the rifle under the scope to compensate for the scope cant. At 100 yds I say the cant will not show up if it was a real situation (or am I mistaken). In other words the article is assuming that a canted rifle will shoot left or right at 100yds.
I say that the only way to test it is to first level the rifle whilst aiming at the bullet hole, then to keep the rifle absolutely still whilst dialling up or down and to see whay your crosshair is doing.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/15/2008 at 09:03
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the difficult part of the entire project is getting the rifle perpend. each time. bench rest shooters spend hours on this. the effects of the cant on subsonic ammunition will be more pronounced than regular, as subsonic is less effected by wind changes.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/15/2008 at 18:54
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The article really deals with scope rotation and not rifle cant.  Scope rotation will have a different effect on the whole matter than rifle cant. 

Imagine an extreme example of scope rotation where the elevation turret is actually at 90 degrees or straight out to the right on a horizontal.  Then when you dialed the elevation turret and then recentered your point of aim, the points of impact would be traveling the horizontal line.  Of course that is a severe case but it illustrates the point.
 
The problem with scope rotation will more readily reveal itself with shooters who crank elevation but I believe that even with just a holdover it would be a problem because with a holdover you run the vertical reticle down through the target.  If you do that and the scope is rotated then running the verticle retical down through the target will shift POI off vertical.
 
Also, if you cant your rifle but the verticle reticle is straight up and down as you hold the rifle in the cant, you will not have a problem.  That is because cranking the elevation or holding over with a straight up and down verticle will also move the rifle in a straight up and down movement and your POI's will be straight up and down.
 
 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/16/2008 at 03:03
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Sakomato, exactly my point! So the article in Longrangehunting is wrong. If the writer had said "on your second shot (after adjusting your elevation) hold the RIFLE absolutely level and then fire the shot" his system would work. But by holding the reticule level, nothing is acheived.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/16/2008 at 09:37
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2 types of cants- if you don't use dial in-- the cant in the scope will be the same as rifle cant. stock cant --can correct scope cant, and usually does with most shooters (what rancid is talking about).
If you can't tell if the the reticle is canted from the factory during manufacture you can't correctly align either.
if the bore has been "blueprinted" to action and the action and mount are dead on then a proper bore alignment and scope alignment can be made such that poi adjustments are on thru scope adjustment.  this is only occurs in top notch usually hand built guns.
poi changes thru scope dial in are usually not a problem with the vast majority of hunters because they define accuracy at a predetermined fixed range- and why hold over and bdc reticles are a better choice for most situations.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/18/2008 at 15:06
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Ok, I am going to use Rancid Coolaid's feeler gage method, but I have Talley lightweight mounts. The front mount has a flat right below the flat on my scope. My question is, how to I know that the mount is sitting on the reciever properly and level with the bore? Oh man this is killing me. I was using my Rapid-Z 800 and the further I shoot the more left I hit. I even hit left when the wind is from the left at very extended ranges.
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Do you hit low and left or just left?  If your reticule is canted, essentially some of your elevation adjustment is functioning as windage adjustment - meaning it ain't all going in as elevation.  If you are shooting left, you should also be shooting low - if it is due to cant.

Does your rifle zero at 100 yards?

Cant is something you can easily work on on the rifle; however, you probably also cant the rifle when you shoot.  A level reticule does you no good if you are canting the gun when you shoot.

I'll go back and read your original post and see if I can offer any help.  The feeler gauges will get the bottom of the scope exactly square to the bottom of the mount - but that is all they do.  For all to function as it should (and the reticule to be of any real value), the vertical line of your reticule must pass through the center of the bore (with no windage correction added in) AND the rifle (and therefore scope) must be level with the horizontal line of the target.


I will try to be of more help, but start with the feeler gauges.

And let me know if you shoot straight left of low and left.
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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I started out hitting low, but increased magnification to make the Rapid-z bring the shots up, but was still hitting left. I didn't know if I was hitting low because I needed to tweak the power setting for the reticle or if it was rotation. Still learning on the Rapid-z, and how accurate their calcuator is.  As far as canting the rifle, it would be a lot easier to not cant it if the reticle was level. I may be canting the rifle due to the reticle being off.

Edited by trigger29 - April/18/2008 at 16:16
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This is not the most accurate but it is fast if it is off very much. Back your eye off the scope to where the reticle is very prominent. visually extend the vertical post to see if it appears to hit the center of the bore. To verify if it is rifle cant put the rifle to your shoulder and point at something that is straight up and down ( Boards in a privacy fence) close your eyes for a few seconds then open them. You should be able to tell if you are canting the rifle by the cross hairs and the cracks between the boards. If you find that you have a poor stance practice by closing your eyes, moving back and forth then open to see if you are square with the world. Bad habits are hard to break. I have spent some time away from shooting ant several old habits have crept up to bite me.
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