Rifle Scopes MOA base clarification

[Racerngr1]

I just put a nice (to me) scope on my 700 with 65 MOA of internal elevationbecause I want to try long range shooting. After getting my scope mounted I learned I'm used 36.5 MOA of internal elevation to get to my 100 yard zero so I basically have 29.5 MOA remaining.

So my question or area I'm looking for clarification is if I use a 30 MOA base by seekins or some one similar do I gain that 30 MOA back which would mean I'm only using 6.5 MOA to get to my 100 yard zero which would give me about 59.5 of usable internal MOA so I can shoot further?

If that isn't the case, what's the point of using a 20 or 30 MOA base?

 

[BobinNC]

Re: MOA base clarification

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Racerngr1</div><div class="ubbcode-body">I just put a nice (to me) scope on my 700 with 65 MOA of internal elevationbecause I want to try long range shooting. After getting my scope mounted I learned I'm used 36.5 MOA of internal elevation to get to my 100 yard zero so I basically have 29.5 MOA remaining.

So my question or area I'm looking for clarification is if I use a 30 MOA base by seekins or some one similar do I gain that 30 MOA back which would mean I'm only using 6.5 MOA to get to my 100 yard zero which would give me about 59.5 of usable internal MOA so I can shoot further?

If that isn't the case, what's the point of using a 20 or 30 MOA base? </div></div>

If your scope has 65 MOA of elevation adjustment, that means in theory you have 32.5 up and 32.5 down. If you have 29.5 MOA left of up adjustment after zeroing, adding a 20 MOA base will now give you 49.5 MOA of up adjustment, and 9.5 MOA down (29.5 MOA - 20 MOA = 9.5 MOA).

A 30 MOA base in your situation will not allow you to get a solid 100 yd zero (29.5 MOA - 30 MOA = -0.5).

49.5 MOA will get a 308 past 1100 yds, as it takes a 175 gr SMK about 39 MOA to reach 1kyds.

 

[Racerngr1]

Re: MOA base clarification

If I bottom out my scope it takes me 36.5 of elevation (up) to get to my 100 yard zero, so if I put a 30 MOA base on it then bottom it out (in theory) it will take 6.5 MOA of up travel to get to my 100 yard zero, if I'm not mistaken.

 

[buffybuster]

Re: MOA base clarification

OK, let me get this straight. WIth a 100yd Zero, you have 36.5MOA of Down and 29.5MOA of UP.

The canted bases, whether 20/25/30MOA, the exact amount is approximate. If you're shooting a .308Win, you'll need about 42MOA to get to 1Kyds. So, a 20MOA canted base will most likely meet your needs and it's the most common amount of cant. You probably will be able to use a 30MOA base and still get a 100yd Zero; the only risk you run is you might get too close to bottoming out and you'll run out of adjustment (windage and elevation).

To be safe, a 20 or 25MOA base would work.

 

[AKAce]

Re: MOA base clarification

In theory, your correct... But Actions / bases are not perfect for them numbers will be Ballpark figures.

Also, keep in mind that the Optics work "Best" the closer to mechanical center they are, some scopes more than others. That said, if your damn near bottomed out @ 100,expect a lil shadowing etc. Figure out what area you will do Most of the shooting and buy a base that matches it and keeps it closer to center.

 

[Racerngr1]

Re: MOA base clarification

Yes, I have 36.5 MOA of down and 28.5 of up elevation. I have a 30-06 and a PST 6-24-60 scope.

 

[VKC]

Re: MOA base clarification

Yes, a canted base will offset your zero and give you "extra" elevation. What ACE stated is true, if you max out your scope, either at the top or bottom of elevation, the spring tension is at the ends and also the clicks/adjustment may not be true.

Consider what caliber your are shooting and what is it's practical range limit, then go from there.

 

[Racerngr1]

Re: MOA base clarification

Perfect, thanks for the clarification everybody.

 

[Aries64]

Re: MOA base clarification

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Racerngr1</div><div class="ubbcode-body">Yes, I have 36.5 MOA of down and 28.5 of up elevation. I have a 30-06 and a PST 6-24-60 scope.
</div></div>
For clarification and the edification of those who do not understand how canted bases actually work (there are plenty here who don't understand this), it needs to be pointed-out that canted bases DO NOT INCREASE the <span style="font-style: italic">physical adjustment</span> of any scope. Only modification of the scope can accomplish that.

A <span style="font-style: italic">forward cant</span> base <span style="font-style: italic">shifts</span> the Elevation Adjustment Range of a scope from the low end to the upper end by a specified amount (20 MOA for a 20 MOA base, 30 MOA for a 30 MOA base, ect). Installing a 20 MOA base will have the effect of shifting 20 MOA of Elevation travel from the low end to the upper end of the Elevation adjustment range, leaving you with approximately 16.5 MOA of "DOWN" and approximately 48.5 MOA of "UP" travel on the scope and rifle you mentioned.


Keith

 

[Racerngr1]

Re: MOA base clarification

Earlier today I ordered a 30 MOA base from EGW. Can't wait to stretch the legs of my rifle.