MOA Base Question?

[Member 34319]

If a base has built in MOA, say 50. I'd need a scope with 50 minutes of adjustment down not total, right. So if my scope has 70 moa total adjustments 35/35 up/down, a 50moa base is out of the question.

Too much going on and my brain is failing me. Just want to verify before ordering a base.

Thanks,

Reno

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[Aero Denezol]

I think the rail just adds to the "up" adjustment on your scope. If you had a scope with 70 MOA adjustment, a 20 MOA rail would give you (35+20) 55 MOA of total adjustment for bullet drop. So you could in theory hit a target with 55 MOA bullet drop. Without the rail you would be limited to 35 MOA.

I don't know if this helps, but that's how I think of it.

 

[dangerranger60]

If my scope had 50 MOA adjustment [25 up and 25 down ] And I can't get enough elevation then I consider a sloped mount.
It won't add to the ammount of adjustment, but will start me out at the amount of slope that the mount adds.
So if I start out with a 20 MOA sloped mount I could get a max of 45 MOA. But I would loose 20 MOA off the other direction. Good Luck DR

 

[DLS]

Your scope's elevation adjustment is a constant, regardless of what the scope is mounted on. It's built into the scope.

A base with built in adjustment changes where the scope is pointing in relation to the barrel allowing you to change the "starting point" of that adjustment.

Think of it this way:

Mount your scope to your rifle using a 0MOA base (a standard base).
Ensure the scope's elevation is adjusted to at the center of its adjustment range.
Place the rifle in a shooting vise and aim at the center of a 100-yard target by moving the vise, not the scopes adjustments.

Now, don't move the rifle,


Now, remove the scope and base without moving the rifle.
Install a +20MOA base on the rifle (remember, it's still in the vise pointed at the target as before)
Mount the scope to the new base (remember, the scope's adjustments are still at the center of their range)

Now look through the scope and see where the scope is pointing. The reticle will be 20MOA higher on the target than before.

This allows you to start elevation adjustments from a "different place".

Let's say you have a scope that on a standard base runs out of elevation adjustment at the range you want to zero the rifle. For grins, with the scope's elevation adjusted to the maximum "Up" setting you can hold dead on at a target at 800 yards, but you want to shoot at 1,000. With your current set up the only way to hit at the farter distance is to hold the reticle over the target.

So you swap out the base for one with built in elevation. This makes the starting point of the elevation range higher than before, and your scope may now have enough range of adjustment to sight in at 1,000 and eliminate the hold over.

What you lose in this situation is down adjustment. Scopes mounted on rifles with +MOA bases can sometimes run out of down elevation and not be able to sight in at closer ranges, say 100 or 200 yards.

So, depending on your cartridge's ballistics, the scope you want to use, and the ranges you want to zero at you have to do some math and may not be able to zero at both close and distant ranges.

 

[TTSX]

Don't go overkill. I've got a scope on a 20moa base that can't travel any further "down" and it still hits 40" high at 650

 

[308]

20moa base was perfect for my old Rem PSS .308 at 600yards

 

[BigGame]

If a base has built in MOA, say 50. I'd need a scope with 50 minutes of adjustment down not total, right. So if my scope has 70 moa total adjustments 35/35 up/down, a 50moa base is out of the question.

Right.

 

[edzz]

May look at XTR Signature Rings. I have a set of these that are preforming well.

Each ring set includes one set of the +/- 0 MOA concentric, one set each of the +/-5 MOA and +/-10 MOA, and two sets of the +/-20 MOA. With these inserts, it is possible to make 0, 5, 10, 15, 20, 25, 30 or 40 MOA of cant in the scope mount.

XTR Rings