Rifle Scopes Mark4 Factory Zero = more ups than downs?

[45.308]

Still reading and much as I can about acquiring a new sight. I read about Mark 4's and if I understand this correct; 70moa adjustment is not 35 each way but in fact internal adjustments are 50moa up and 20moa down. Correct? Is this common with other scopes or just a Leupy thing, or am I off track?

 

[Surgeon308]

Re: Confused about internal moa adjustments?

If you're talking about vertical for instance, it depends on where you're "zero" is.

Say you mount your scope and have to adjust it from mechanical center to get zeroed on your target and your preferred range, then no, it won't be 35 and 35.

Only by chance will a person mount mount a scope and their zero (100yds for example) will be mechanically in the center of their scope. Will always be a little, up/down/left/right from mech. center.

 

[45.308]

Re: Confused about internal moa adjustments?

This is what I was referring too, I hope it is OK to post it, a review from another web site on the Mark4:

<<The factory says there is 65 MOA of adjustment, though this particular sample had 76 MOA of vertical adjustment, 27 MOA down from factory zero and 49 MOA of up. There should be enough "slop" either direction to zero the scope at 100yards with most typical 308 rifles and still have all the adjustments needed to get to 1000y without a slanted base. You will notice there is a bias in the factory zero to allow for more up MOA.>>

 

[One-Eyed Jack]

Re: Confused about internal moa adjustments?

"Factory zero" simply means that's how the scope came from the factory. You can't rely on the factory presetting the erector position to "optical zero." When the erector is at "optical zero", you can rotate the scope around the central axis of the tube and the center of the image will not spin or even wobble. If the erector isn't "optically zeroed", the point at the center will spin in a circle as the tube is rotated.

To determine whether there is an up "bias", you first have to optically zero the erector, then determine the up and down travel. But don't count on Leupold centering the erector for you.

 

[Swamper]

Re: Confused about internal moa adjustments?

I always thought the "erector" was the conveyance which responds to the power/magnification ring movement. A lens moves in/out on a worm-drive to yield a higher lower magnification. Power ring moves the worm-drive, which moves the lens...

Reticle movement conrols for each turret are the same. The limiting factor is the reticle position and tube diameter. Some 30mm scopes have 1" tubes which limit the turret movement to 50-60 moa. Might see reduction in reticle movement because of tube length and scope design as well.

Some of the older Leupold mark 4 and LRT scopes could be adjusted to center with their cams/turret dials removed.

 

[45.308]

Re: Confused about internal moa adjustments?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: One-Eyed Jack</div><div class="ubbcode-body">"Factory zero" simply means that's how the scope came from the factory. You can't rely on the factory presetting the erector position to "optical zero." When the erector is at "optical zero", you can rotate the scope around the central axis of the tube and the center of the image will not spin or even wobble. If the erector isn't "optically zeroed", the point at the center will spin in a circle as the tube is rotated.

To determine whether there is an up "bias", you first have to optically zero the erector, then determine the up and down travel. But don't count on Leupold centering the erector for you. </div></div>

You sort of lost me but I take it you are saying no!