Leveling Cross Hairs, Why?

[Old Moss]

   OK Gents hear is one I have not seen answered lately.

Why do you need to level your cross hairs on your scope perfectly with the bore/action?

If one looks at the physics I cannot find a reason.  If the scope is canted slightly but solidly mounted and the shooter levels the cross hairs, holding the gun the same way each time the bullet will leave the barrel the same way each time (with everything remaining equal) the group size will be the same and once zeroed - accuracy will be good.

Now with iron sights, absolutely.  Even with peep sights it makes since.  But with a scope 2+2 doesn't add up to 4.  So please explain, or is this just another means to spend are money on gadgets.

Actually does it not make more since to shoulder the weapon establish that repeatable position that you will be shooting your best from and level the cross hairs to the shooter's eye to make one come back to the same hold each time.  This makes more accuracy since to me.  Look at how silhouette shooters sometimes mount there scopes. 

Thanks Folks your always a wealth of knowledge    Old Moss

[DalesCarpentry]

I think the most important reason would be if you were shooting long range and dialing in elevation and windage. You would be off target because of the cant. Dale

[Old Moss]

   Dalescarpentry,

Good point, but if one shoots with the reticule always leveled to the shooters eye then making elevation adjustments will still work.  It would hold true if - yes the shooter was holding the rifle action level and seeing the cant in the scope - you would be correct, because the movement of the reticule would be at an angle. 

So again, my hypothesis still has a glimmer of hope.

Another question arises "one should always level the cross hairs to the ?What? The action, The bore, the bore is round it does not have a level.  The action or the stock are mechanically separated and have no clear points of reference, so can one really tell when it is level or not?  When one shoulders a weapon how it is held and fired is different than placing it in a vice and putting a level on some flat part of the gun, wouldn't you say?

Maybe I have been thinking about this to much?    But it helps me try to keep my old mind sharp 

Dalescarpentry,  you may have something.  Am I explaining my self well enough?  Thanks  What do the rest of you all think out there?  Old Moss   

[torpedoman]

if your hunting and see an elk whip out the range finders 350 yds. OK adjust the ao on the scope for 350. figgure drop dial it in, figgure wind dial it in , shoulder gun . Now were did that darn elk go? Maybe we have way to many toys.

[dave375hh]

If your cross-hairs aren't level to the bore, your adjustments will be off. The adjustments are relative to the bore not your eye. If they are canted to the left and you add elevation the shots will go higher but to the right. This is also true for Kentucky windage at any elevation other than what it's zeroed for. No one holds a gun consistantly the same to change this factor. The factor has nothing to do with gun mount. The cross-hairs move relative to the bore not your shoulder or eyes. Do it right or pay someone to do it for you, you'll be happier in the long run.

[victorcharlie]

I think this is more important when shooting off the bench and necessary in making predictable scope adjustments.

It's not hard to level the cross hairs however and IMO is "best practice".

[charles p]

My question to you is, why wouldn't you want your crosshairs in a level position?  Only reason I can think of is that maybe you always shoot from the identical canted position?

I prefer level crosshairs - they just make me feel better.

[Old Moss]

   Folks,  Not wanting to rill any feathers! 

And I agree with you all.  Let me put it another way the scope is perfectly level when you shoot, but the rifle is slightly canted - does that really cause the rifle to shoot less accurately?  I once did this on purpose canted the scope slightly and then proceeded to set the gun up in sandbags making the scope level not the gun.  I was able to make changes in windage and elevation just like I normally did dial the rifle in and it shot a normal 1" group.

So please read my posts again and think about what I'm saying.  I really want to know why good accuracy is dependent on finding the centered & leveled bore and matching the cross hairs to that leveling point.  And what is the point or line you are leveling too?  Thanks and I really do appreciate the comments!     Old Moss   

[Dave in WV]

If the axis of the rifle and crosshairs are not aligned (plumb) the zero you have is for the range,windage & elevation, the scope is zeroed for. If the scope and rifle are plumb your windage (minus wind) will stay the same. With the canted reticule the windage will change with range. How much is dependant on the amount of cant and range. If you understand the concept of how WW II fighters had their guns converge at a given range you'll see what I'll getting to. The wing mounted machineguns on WW II fighters converged at a set range. The bullets crossed beyond that range and were still converging at a range shorter than the bore sighted range.

[billy_56081]

Well first of all it is going to be normal for most people to try to level the cross hairs while aiming the gun. Now if the cross hairs are not leveled this will cause you to cant the gun one way or the other. Now with the gun canted one way or the other, the scope is not centered over the axis of the bore. The bullet will only cross the line of the bore at one point. On a reticule that is level, the bullet will cross the line of the bore at 2 places. If the rifle is canted the bullet will strike to the left or the right of where you intend to hit if not at the zeroed range. The amount that it will be off is dependent on how high the scope mount is and how far off to the left or right of over the center of the bore. the amount will be generally very little but in precision shooting it would be of importance. For shooting at a set range, being perfectly level isn't so important, being consistent on your level is important. The left right crossing error will only show up if shooting at different distances and using hold over or elevating your adjustments on the turrets.

[DalesCarpentry]

  Folks,  Not wanting to rill any feathers! 

And I agree with you all.  Let me put it another way the scope is perfectly level when you shoot, but the rifle is slightly canted - does that really cause the rifle to shoot less accurately?  I once did this on purpose canted the scope slightly and then proceeded to set the gun up in sandbags making the scope level not the gun.  I was able to make changes in windage and elevation just like I normally did dial the rifle in and it shot a normal 1" group.

So please read my posts again and think about what I'm saying.  I really want to know why good accuracy is dependent on finding the centered & leveled bore and matching the cross hairs to that leveling point.  And what is the point or line you are leveling too?  Thanks and I really do appreciate the comments!     Old Moss   

It would seem that you have made up your mind on this subject. Other experts that have devoted their lives to long range shooting seem to level their cross hairs There has to be a proven reason behind it and yes you have now Russeld my feathers. Dale

[billy_56081]

Another thing you may have seen recently in the shooting world. Is the new Leupold scopes with the front lens that is cut out to allow you to mount the scope as low to the bore as possible. The closer the scope is to the axis of the bore the less effect canting the gun has on bullet impact.

[Old Moss]

      DALESCARPENTRY - Sorry your feathers got out of sorts,  I had not made up my mind on this subject,  I was just pushing a little to get an answer that would make some since to me, and I did.  I thought this was a place for learning and discussing the shooting discipline.  I meant no disrespect at any time, by the way I have been leveling my cross hairs for over 40+ years and new that it was the right thing to due, I had learned this from some of those experts who dedicated their lives to long range shooting some 30 years ago.  I did not wish to offend, please accept my apology. 

Dave in WV and billy_56081  Thank-you  now it begins to make some since! 

Since the scope is elevated above the bore the axis point which one is leveling too, is half way in between the scope center and bore center with an invisible line going through both vertically.  This axis for accuracy must be maintained.  If the scope cross hairs are not level/centered and then one compensates to level them one would offset the scope - making the whole system off axis.  The scope would then lie either left or right and therefore the bullet cannot cross that convergence point like the WWII fighters had to do.  The point of impact varies and is sporadic and accuracy suffers!!!

How amazing the shooting discipline, rich with science and knowledge.  Thanks all for the discussion and explanation.    Respectfully, Old Moss 

P.S. Graybeard if I have been inappropriate please provide feedback I wish to be a positive contributor and not a negative.  Again thank-you for this great website.  Old Moss