MOA question.

[Guest lukethetechguy]

I don't quite understand how MOA works when it comes to scopes. If I'm wanting to shoot really long distance I can get a 20 MOA scope mount. Please explain.

Thanks

[Jonnin]

MOA is just a trig measure of angles.   That is all it is, is a measure of the angle between where you aimed vs where the bullet hit.  Naturally, this can be used to offset the drop caused by gravity at longer ranges, or a constant wind effect, or the like, so your point of aim and point of impact are the same at some range.   It is also correcting for the fact that your scope and barrel are approximately parallel instead of using the same center line. 

 

I am not sure what MOA on mounts might mean, though.   It sounds like a misuse of the term to me?

 

What you are probably looking for is a high dollar scope with good, easy to use and easy to understand adjustments in the field.   The scope mounts... do not usually enter into it very much, you just need them to be solid/secure and at the correct height etc.

Edited December 27, 2012 by Jonnin

[atlas3025]

Some mounts are tilted so that you get extra down adjustment on the scope to allow for the large amount of bullet drop at long ranges.  I suspect that is what it refers too...I believe it means it gives you an additional 20MOA of bullet drop adjustment range over what your scope is normally rated for.  So if your scope had 100 MOA of elevation adjustment, it means if the scope lines up perfectly with a normal scope mount, you have 50 moa up and 50 moa down.  With the 20 MOA mount you will have 30 up and 70 down...but you rarely need a significant amount of up so that is a fine trade for a long range gun.

[Guest J.boyette]

Ok,

 

 Here is the skinny.

 

MOA mounts:

 

 A forward canted mount can have a value lets call it 20 MOA. So this places your line of sight 20 MOA lower then a flat mount.

 

 EXAMPLE:

 

 Lets say your Leupold has 60 MOA of total adjustment in its elevation knob. Lets also say that 30 MOA = 100yds. So once you ZERO the optic to have the same point of impact as the line of sight at 100yds you are at a 100yd ZERO. Now if you dial DOWN you have 30 MOA of unused elevation adjustment. When you dial UP you have 30 MOA of useful adjusment. do to the fact this fake optic has 60 MOA in it and it just so happens 100yds falls at the middle (never works like this)

 

Anyhow, you start to shoot long range. So here are the MOA adjustments for distance:

 

100YDS = Z

200YDS = 01.25MOA UP

300YDS = 05.00MOA UP 

400YDS = 08.25MOA UP

500YDS = 12.00MOA UP

600YDS = 16.25MOA UP

700YDS = 21.00MOA UP

800YDS = 26.50MOA UP

900YDS = 32.50MOA UP

1000YDS=39.50MOA UP

 

So as you can see at 800yds you are at 26.50moa above ZERO you only have 3.5MOA left in the optic, the only way ot hit 900 and 1000yds is to hold over with a reticle like a Mil-Dot or MOA but thats a diffrent topic.

 

If we take the same optic with 60 MOA and at 100yds we have 30 MOA above and 30 MOA below and add a 20 MOA base we will now cant the optic forward by the slope of the base.

 

Once installed will now give us 50 MOA UP from 100yds and 10 MOA below the ZERO!!!!!

 

30 MOA in the optic + 20 MOA from the base = 50 MOA

 

This 20 MOA base is just letting us use more of the elevation in the given optic. it does not GIVE you more elevation, its letting you use more of what is built in the optic.

 

The key to know if you need a base is to ZERO at the distance you want, then dial on 48 MOA above that ZERO if you got 48 MOA then you do not need the base. If you can not dial to 48 MOA go back to ZERO and see how much below ZERO you have, and you should have more then 25 MOA if so get a 20 MOA base.

 

 If below ZERO you have 15 MOA then yo must get a diffrent optic or know you will zero at 200yds and thats as close as yo can dial down to with a 20 MOA base.

 

Hope that helps

 

John

Edited December 28, 2012 by J.boyette

[RWF]

just a note, also for long range farther than 600 yards i would recommend not getting a 1" scope but a 30mm as a rule larger tube the more adjustment range. and when you do the dope do not pay any attention to the inches. ONLY THE MOA