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Rifle Scopes 20 moa base necessary or no?

Re: 20 moa base necessary or no?

Necessary? It depends, on your rifle, your load, and the scope you choose.

For example:

308 Winchester - most loads need 10-11 Mils (34 to 38 MOA) to reach 1K yds. Mount a scope that has only 13 mils of elevation (45 MOA)like a Bushnell 4200 6-24x50MM Tactical on a 0 MOA base.

Now you have 6.5 Mils up (22 MOA) and 6.5 Mils down (22 MOA). No reaching 1K yds without a hold over, from a 100 yd zero.

Add a 20 MOA (5.5 Mils) base to the above combo, you now have available in theory 12 Mils of elevation (41 MOA), and reaching 1k yds is usually not a problem.

Choose a different scope, like a Fixed power Super Sniper, or a 3.5-15x50mm Night Force for example, you have over 110 MOA on tap, so a 20 MOA base is not really needed, but never hurts.

In short, your rifle, your load, and your scope, plus what you want to accomplish, should drive your choice of bases.

One size does not fit all.

Bob
 
Re: 20 moa base necessary or no?

I mean you usually need a base right? Well why not get one with a cant just to be sure? It might end up on a rifle later with a loopier trajectory or maybe under a scope with less adjustment as was mentioned. More versatile overall I think.
 
Re: 20 moa base necessary or no?

I would get the 20 moa base, because once you start shooting at 600 you will probably end up going further out, and for that you will most likely need the extra 20moa. But I guess it would depend on if you think you will ever shoot farther than 600.
 
Re: 20 moa base necessary or no?

20 MOA of up elevation for nothing?

Yea, I'm in.

It doesn't hurt anything, but can be beneficial later on if you decide to shoot out further
 
Re: 20 moa base necessary or no?

Sorry, forgot to mention it will be going on a .308 rem700. I'm sure once I "master" distances out to 600 I will be itching to go farther.
Sounds like I might as well go with the 20moa base anyway. I'll most likely be getting a super sniper 10x42 scope. Just trying to piece everything together.
This is yet another "getting out of the military" present to myself lol
 
Re: 20 moa base necessary or no?

I removed my 20MOA base when I was running a Falcon Menace, I found that with my 100 yard zero, I was well below the come up index marks and I wanted to see them.
Personal preference.
I am now running an IOR 3-18 and really don't need one anyway.
 
Re: 20 moa base necessary or no?

The trouble is that with a 0 MOA base and a 100m zero, with the scope clicked up for say a 800m shot, your not going to have much windage adjustment available.

A 20moa base will solve this problem as well the more obvious one of having enough elevation....
 
Re: 20 moa base necessary or no?

I have been in the process of selecting a base and was interested in purchasing a 20 MOA base, but I am somewhat confused, and I could use the advice of those who know. On a 20 MOA base, I thought the purpose was to raise the front of the scope higher so that the line of sight on the scope was higher than the line of the barrel's bore, but I have noticed that the front of the scope is lower. This does not make sense to me.
 
Re: 20 moa base necessary or no?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RandyD</div><div class="ubbcode-body">I have been in the process of selecting a base and was interested in purchasing a 20 MOA base, but I am somewhat confused, and I could use the advice of those who know. On a 20 MOA base, I thought the purpose was to raise the front of the scope higher so that the line of sight on the scope was higher than the line of the barrel's bore, but I have noticed that the front of the scope is lower. This does not make sense to me. </div></div>

What may be confusing you is that a 20 MOA base is slightly elevated at the <span style="font-style: italic"><span style="font-weight: bold">rear</span></span> compared to a 0 MOA base.

Think of a rear sight on a rifle or handgun. To raise the bullet impact you raise the rear sight...same principle.

TC
 
Re: 20 moa base necessary or no?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BobinNC</div><div class="ubbcode-body">Necessary? It depends, on your rifle, your load, and the scope you choose.

For example:

308 Winchester - most loads need 10-11 Mils (34 to 38 MOA) to reach 1K yds. Mount a scope that has only 13 mils of elevation (45 MOA)like a Bushnell 4200 6-24x50MM Tactical on a 0 MOA base.

Now you have 6.5 Mils up (22 MOA) and 6.5 Mils down (22 MOA). No reaching 1K yds without a hold over, from a 100 yd zero.

Add a 20 MOA (5.5 Mils) base to the above combo, you now have available in theory 12 Mils of elevation (41 MOA), and reaching 1k yds is usually not a problem.

Choose a different scope, like a Fixed power Super Sniper, or a 3.5-15x50mm Night Force for example, you have over 110 MOA on tap, so a 20 MOA base is not really needed, but never hurts.

In short, your rifle, your load, and your scope, plus what you want to accomplish, should drive your choice of bases.

One size does not fit all.

Bob





</div></div>

+1

I mounted that very Bushnell on my Savage model 10 in .308 last Wednesday. 100 yard zero left me with 11 MIL of verticle travel.
 
Re: 20 moa base necessary or no?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Top Cat</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RandyD</div><div class="ubbcode-body">I have been in the process of selecting a base and was interested in purchasing a 20 MOA base, but I am somewhat confused, and I could use the advice of those who know. On a 20 MOA base, I thought the purpose was to raise the front of the scope higher so that the line of sight on the scope was higher than the line of the barrel's bore, but I have noticed that the front of the scope is lower. This does not make sense to me. </div></div>

What may be confusing you is that a 20 MOA base is slightly elevated at the <span style="font-style: italic"><span style="font-weight: bold">rear</span></span> compared to a 0 MOA base.

Think of a rear sight on a rifle or handgun. To raise the bullet impact you raise the rear sight...same principle.

TC </div></div>

Thanks.
 
Re: 20 moa base necessary or no?

Move the front sight toward the actual POI, the rear sight toward the desired POI.

While it can be quite feasible to skip the sloped base and still reach the desired scope adjustment, this can place the LR zero rather close to the elevation adjustment range limit. Because of many scopes' internal configuration, this can simultaneaously end up restricting windage adjustability.

Even if you don't 'need' the slope supplementation, it can make sense to employ it anyway. If this puts you in a postion of being unable to reach the adjustment for the minimal distances, a 'hold-under' technique can be a quick and dirty means to resolve the issue. Because this occurs in the close foreground, excellent accuracy can still be achieved once the hold-over value becomes established and accustomed.

Greg
 
Re: 20 moa base necessary or no?

By the way. On my set up I was still left with 1.2 MIL down travel which is way more than will ever be needed to make a shot under 100 yards. I only need -.1 MIL to make a 50 yard shot. The 20 MOA base did everything I needed it to.
 
Re: 20 moa base necessary or no?

....Better to have it and not need it, than to need it and not have it.
wink.gif
 
Re: 20 moa base necessary or no?

I have a Near base with 30moa. With the Badger rings I'm using temporarily on this rifle I'm dialed absolutely at the bottom of the S&B PMII with a 100yd zero. No place to go but up!
 
Re: 20 moa base necessary or no?

What options do you have if you are shooting a semi-auto weapon? The base is already "installed". I was looking at a 6-24X50 IOR FFP scope but am concerned about the 16 mils of adjustment (which I am pretty sure means only 8 mils in either direction). This would be for a .308 (POF or maybe an OBR, haven't decided yet) and I would be interested in hitting 800-1000yds (eventually).

Do they make 1 piece mounts or scope rings with a built in cant?