Rifle Scopes Bizarre zeroing with a Mark 4 M1 3.5-10x...

[BigBrother]

Hey all- hope nobody minds my outpouring of posts recently- just trying to narrow some stuff down so I can finally go out and shoot this season

I had a real pain in the ass trying to find the culprit behind a zeroing problem with my rig (just search for my posts- some of the threads go on and on with info). But the point is, I finally tracked it down to the scope. For whatever reason, my particular model of Leupold zeroes very high compared to its optical zero. With my 20 MOA base, it zeroes at 100y at its actual optical zero (35 MOA up, 35 MOA down). On a flat top AR, it zeroed with only 20 MOA up!

So after a lot of experimentation a gunsmith put another Leupold on there he had, which was zeroed on another rig with 20 MOA base, and the zero was correct (about 20 down, 80 up). It was I think a 4.5-14x model.

Anyway, that one scope I have has actually been swapped three times by Leupold, so I can only conclude it's the model. Has anyone else, with this exact model:

http://leupold.com/tactical/products/sco...m1-front-focal/

Seen this issue? Then I'll know if I should just swap Leupolds or dump the brand entirely..

 

[BobinNC]

Re: Bizarre zeroing with a Mark 4 M1 3.5-10x...

BigBrother,

A couple of questions first:

Did Leupold return the same scope to you 3 times, or did they send three different scopes?

What 20 MOA base are you using, and did you bed it?

What rifle is the base mounted on?

What rings are you using?

I ask these questions, because the problem can only lie in four areas: The scope; the base; your receiver, or your rings, and/or some combination of all three.

Let's go back to your math:

Leupold 3.5-10x40MM M1 FFP has a "listed" 65 MOA of adjustment.
Leupold 4.5-14x40MM M1 & 4.5-14x50mm has a "listed" 100 MOA of adjustment.

On your rifle with 20 MOA base you said you had, 35 up and 35 down. Meaning the scope, or your base, or your rifle, or your rings, has 15-20 MOA of up angle.

On the Flat top AR you had only 20 up. leaving 45 down. Meaning the scope or your rings has 15 MOA of up angle.

When you mounted the 4.5-14 you now had 80 up and 20 down. It should have had 70 up and 30 down. Somehow you acquired an extra 10 MOA of down adjustment.

I not letting Leupold off the hook yet, but there is something strange about the numbers. The FFP is a new design for Leupold, and it would not surprise me in the least if all the Bugs are not worked out yet.

I do know that early Leupold's with M3 turrets had a built in 20 MOA down slope, which then produced some strange results for their users when a 20 MOA base was added. But that's clearly not your problem.

What did Leupold say all three times they got the scope back?

Thanks,

Bob

 

[BigBrother]

Re: Bizarre zeroing with a Mark 4 M1 3.5-10x...

Bob, you've now stepped in it

. I'll gladly direct you to the previous threads where I went over every detail with painstaking thoroughness...

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1050901&page=1

Enjoy

. Oh, also, not sure if it's listed there, but base has also now been switched to another of the same model and confirmed by Badger to be a 20. You may just want to message me on this topic since I want to keep this thread open for the original question. Thanks.

 

[BobinNC]

Re: Bizarre zeroing with a Mark 4 M1 3.5-10x...

You don't have to direct me to anything. I'm sorry I tried to help.

My Bad,

Bob

 

[BigBrother]

Re: Bizarre zeroing with a Mark 4 M1 3.5-10x...

Woops, didn't mean it if it came off sarcastically. I meant to say it's a pandora's box that I hate having to drag people into because it's SUCH a long history- by stepped in it I meant you've now entered the saga of suck that I've had to deal with.

Quite the contrary- I offered the link and mentioned the thoroughness to give you all the background info if you wanted it.

Apologies if it came off otherwise!