moa on a mount?

[ekkthree]

what does it refer to when they list a scope mount's moa?
if it's what i think it is (height) then why do i want it?

[tozan]

When shooting long distance most scopes will not have enough elevation to zero the scope in at those ranges. By adding a 20 moa base you will be able to readjust the scope to hit targets out to 1000 yards or more.

[Ki6vsm]

And just to be clear, minute-of-angle is not a measure of length or distance. It's a measure of angle.

When you see a mount that is described as 20 MOA it means that the top of the mount (where the scope attaches) is tilted 20 MOA forward relative to the base (which is aligned with the rifle's bore).

Read a little more here if you like:

https://www.nssf.org/shooting/minute-angle-moa/

[tony270]

Originally Posted by ekkthree

what does it refer to when they list a scope mount's moa?
if it's what i think it is (height) then why do i want it?

This info only relates to the 20 moa that is built into the Vortex 20mm cantalever scope mount.

I purchased the 20 MOA mount for this preadtor hunting rifle. The hub bub that the extra MOA would affect the shooter is not in my case. As a matter of fact yesterday when I bore sightted at 25 meters, the bore sight was dead on.

So late yesterday evening I went and zero it at 25 meters. The first 3 shots were high (red circle), then after adjusting 8 clicks down, I take 1 shot (blue circle), then adjust 2 clicks down, 4 clicks right, then take 1 shot (yellow), then adjust 2 clicks left, and then shoot 5 rounds (black circle), then I move to top right, then to top left, then to bottom left.

I shot a total of 20 rounds, next time will be at 100 yards.

So from what I can discern, it depends on the mounting system, my advise is to consult the manufacture, that's what I did.









Why would I need the 20 MOA, why not, may be I want to shoot the side of a barn at 800 meters...or one day I could use the mount on a long range rifle, all I know is that in my case it only gave me more.

[smoothy8500]

I thought MOA was dead....

[Ki6vsm]

Originally Posted by tony270

So from what I can discern, it depends on the mounting system, my advise is to consult the manufacture, that's what I did.


Why would I need the 20 MOA, why not, may be I want to shoot the side of a barn at 800 meters...or one day I could use the mount on a long range rifle, all I know is that in my case it only gave me more.

I love the desert pics. That's where I shoot, though down in the "low desert".

Yep, you may or may not need the 'help' of a 20-MOA mount. I found that I did not, with my set-up. I was hitting a plate at 1000 yds using a standard Laue mount on my 6.5 Grendel AR. But my Scope (SWFA 10x) has something like 120 MOA of total elevation adjustment, which is pretty amazing. So I had NO problem dialing up the 38-40 MOA I needed to reach out to 1000. And I had more Ms-OA to spare.

On the other hand, at the advice of a shop, a friend of mine put a 20 MOA scope mount under a 1" Nikon scope. This was on an AR. He quickly found out that he did not have enough elevation in travel even to zero that "223" scope 100 yds. He's selling that 20 MOA mount and got a straight mount. (In hindsight, he should have bought a 30mm scope, not a 1".)

[SlowDrifter]

Originally Posted by Ki6vsm

I love the desert pics. That's where I shoot, though down in the "low desert".

Yep, you may or may not need the 'help' of a 20-MOA mount. I found that I did not, with my set-up. I was hitting a plate at 1000 yds using a standard Laue mount on my 6.5 Grendel AR. But my Scope (SWFA 10x) has something like 120 MOA of total elevation adjustment, which is pretty amazing. So I had NO problem dialing up the 38-40 MOA I needed to reach out to 1000. And I had more Ms-OA to spare.

On the other hand, at the advice of a shop, a friend of mine put a 20 MOA scope mount under a 1" Nikon scope. This was on an AR. He quickly found out that he did not have enough elevation in travel even to zero that "223" scope 100 yds. He's selling that 20 MOA mount and got a straight mount. (In hindsight, he should have bought a 30mm scope, not a 1".)

OK lost me....if he didn't have enough elevation at 100 yards he probably had the 20moa base mounted backwards. Mounted correctly, he may have run out of 'down," but not "up" elevation. Second, the few extra clicks a 30mm vs. a 1" tube offers wouldn't have solved that problem.

On the 20moa base explanation, it doesn't give you any more adjustment, you just borrow from the bottom to add to the top. All things being equal, let's say your scope is at center elevation and dead on at X-yards. Let's also say your scope has a total of 80 minutes of internal adjustment. 40 up and 40 down. You throw on a 20moa base. You have to crank down 20moa on the scope to re-gain that zero. You just borrowed 20 minutes of downward adjustment to loan 20 minutes of upward adjustment. The only way to get it back is to remove the 20moa base. So, from that same x-range you were zeroed at, you now can go up a whopping 60 minutes if you want, but you'll run out of adjustment at 20 minutes going down.

edited to add an apology. You didn't say whether your friend ran out of up or down elevation. I can see him running out of down.

[champu]

Originally Posted by SlowDrifter

On the 20moa base explanation, it doesn't give you any more adjustment, you just borrow from the bottom to add to the top. All things being equal, let's say your scope is at center elevation and dead on at X-yards. Let's also say your scope has a total of 80 minutes of internal adjustment. 40 up and 40 down. You throw on a 20moa base. You have to crank down 20moa on the scope to re-gain that zero. You just borrowed 20 minutes of downward adjustment to loan 20 minutes of upward adjustment. The only way to get it back is to remove the 20moa base. So, from that same x-range you were zeroed at, you now can go up a whopping 60 minutes if you want, but you'll run out of adjustment at 20 minutes going down.

^this.

The idea of a 20 MOA scope mount (or 20 MOA rail/base) is predicated on the fact that you are otherwise going to zero your scope at a range that’s near the mechanical center of the scope, dial up for longer distances, and generally waste half of scope’s elevation adjustment range.