Rifle Scopes MOA base question, is there too much?

[viav13]

Is it possible to have a base with too much MOA?

What im getting from a MOA base is that it takes the natural aiming point of the scope from the middle (mechanical zero) and movies it higher so you will have a higher range of clicks to adjust for the drop of the round.

That might be horribly explained...

If i have a scope with 80 MOA overall, 40 up and 40 down, then add a 20 MOA base. That would give me 20 up and 60 down. Correct?

So in this case would a 45 MOA base would be too much?

But it wouldn't be to much for a scope with a higher MOA on the up?

If this is correct, then a MOA base would be more based on the scope you are using and not the rifle its going on.

 

[Boomholzer]

Re: MOA base question, is there too much?

Your on the right "track". Note that the optical center of the scope travel and the zero at range has no reliable point or guarantee.

The rifle and load has it's inherent limitations......so in practical purposes being over Xmoa is pointless.

 

[Lindy]

Re: MOA base question, is there too much?

You may be confusing which way you dial for longer ranges with which way the reticle moves.

Referring only to dialing more elevation at longer distance, putting a 20 MOA base on a scope with 40 up and 40 down will allow you to dial elevations of <span style="font-style: italic">about</span> 60 up and 20 down.

You can get too much elevation in the base, if you get so much that you can't establish a short-range zero, like at 100 yards or meters.

 

[BobinNC]

Re: MOA base question, is there too much?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: viav13</div><div class="ubbcode-body">Is it possible to have a base with too much MOA? <span style="color: #FF0000">YES</span>

What im getting from a MOA base is that it takes the natural aiming point of the scope from the middle (mechanical zero) and movies it higher so you will have a higher range of clicks to adjust for the drop of the round. <span style="color: #FF0000"> No, it moves it lower</span>

That might be horribly explained...

If i have a scope with 80 MOA overall, 40 up and 40 down, then add a 20 MOA base. That would give me 20 up and 60 down. Correct?<span style="color: #FF0000">No, 60 up and 20 down</span>

So in this case would a 45 MOA base would be too much?<span style="color: #FF0000">YES</span>

But it wouldn't be to much for a scope with a higher MOA on the up?<span style="color: #FF0000">With a Higher overall adjustment range </span>

If this is correct, then a MOA base would be more based on the scope you are using and not the rifle its going on. <span style="color: #FF0000">YES</span></div></div>

 

[michaelt454]

Re: MOA base question, is there too much?

Don't mean to hijack here, but along the same lines, I'm about to mount a nightforce 5.5-22 with ~100 MOA of travel on a 50 cal. I bought the gun used and it came with two canted rails, a 15 MOA rail and a 50 MOA, problem is the 15 MOA base gets me to the ragged edge (requires 65.5 MOA) at 2000 yards, with AMAX's but with other bullets that I load, I need more base, so when my rings get here, I plan on laying the scope in the ring bases on the 50 MOA base without mounting permanently, then trying to bore sight at 100 yards. I think that will be close enough to tell me if I'm going to make it with a 100 yard zero? Anybody know if that is the proper way to approach this problem, or should I just mount it on the 15 MOA base and stop thinking that I will ever to be able to hit anything at 2000 yards anyways, especially with any bullet other than an AMAX?

Thanks

Michael T.

 

[Lindy]

Re: MOA base question, is there too much?

If you put a 50 MOA base on that gun, it is unlikely that you will achieve a 100 yard zero.

Bases of that sort were intended to be used to establish extended-range zeroes for those weapons, to ensure that there was enough scope travel to be able to dial long distances.

For example, some early production models of the Barrett M82A1 came with built-in 60 MOA bases, and the rifles were normally zeroed at 1000 meters.

Scopes with enough elevation travel to go from a short-range zero to 2000 yards are rare.

A .50 firing Mk 211 ammunition, for example, zeroed at 500 meters, will require somewhere in the vicinity of 98 MOA to get to 1800 meters.

On the other hand, you can always hold under using the reticle on shorter range targets.

 

[michaelt454]

Re: MOA base question, is there too much?

Thanks for the info Lindy, so you are saying that I should stick with the 15 MOA base if I want a 100 yard zero? According to JBM ballistics, my 750 grain AMAX load at 2800 fps requires 65.5 MOA at 2000 yards with a 100 yard zero. Shouldn't I have ~65 MOA of upward adjustment with the NXS and the 15 MOA base? Or am I flat missing something here?
I defer to your superior knowledge on all things even remotely related to what we are discussing here.

Thanks

Michael T.

Anyone who quotes Massad Ayoob is GTG in my book.

 

[Lindy]

Re: MOA base question, is there too much?

Assuming that the scope really has pretty much exactly what the manufacturer specifies for that scope, i.e., 100 MOA of travel, here's the problem with the 15 MOA base:

Put the 15 MOA base on, and you <span style="font-style: italic">should</span> then have about 65 MOA up, and 35 down. But it takes about 4 MOA of "up" to establish a 100 yard zero, depending on how much your load drops from the muzzle to 100 yards and how high the scope is above the bore.

So, now we're down to 61 MOA or so, if everything is correct, and that won't get you to where you want to go.

In addition, as the recticle gets near the end of it's travel, it's being constricted in lateral movement, and you may not be able to dial enough windage, which you may need at those longer ranges - it's not unusual at extreme range to need more wind adjustment than you can hold on the reticle.

So, you'd be a lot better off with a 25 or 30 MOA base, and you'd still be able to get a 100 yard zero.

A base is pretty cheap compared to the cost of those rounds you're going to shoot, so it seems to me to be a reasonable investment.

 

[michaelt454]

Re: MOA base question, is there too much?

Being that I have no experience with optics other than Leupold Vari X 3's for hunting, help me get this straight, at the extremes of elevation travel, the windage movement is diminished so that the advertised 60 MOA of windage adjustment could become 50 or less? I did not know that handy piece of info. Would you see a problem with a 200 yard zero and the 50 MOA rail? I'm behind here I know, but I'm trying my hardest to catch up.

Michael T.

 

[Lindy]

Re: MOA base question, is there too much?

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">...at the extremes of elevation travel, the windage movement is diminished so that the advertised 60 MOA of windage adjustment could become 50 or less?</div></div>

That's correct. The exact amount of that restriction varies. However, as long as you're not <span style="font-style: italic">very</span> near the limits of travel, I expect that you'd not have a problem.

I think the 50 MOA base is just too much for that scope, as it's going to put you very near the bottom, and the manufacturer's specifications are not always precise for a given scope. And you may well need some windage adjustment just to achieve a short-range zero if the base mounting holes are not precisely in line with the bore.

I'd recommend a 25 or 30 MOA base.

 

[cdmurphy]

Re: MOA base question, is there too much?

Michael,

If you need a base in the neighborhood 30 or 40 MOA, I could use either of your current bases for measurements, and make you up a custom one. I just finished making a 50 MOA titanium base for a Lawton 8500, which is probably close to the size of your rails.

PM me if you would like to discuss this further.

- Cameron

 

[michaelt454]

Re: MOA base question, is there too much?

Cameron, PM sent. Thanks for the input guys I really appreciate it. I have had these questions for a while, but really couldn't get anyone to take the time to answer my questions in depth. Guys like yall are why I read this forum religiously.

Michael T.

 

[viav13]

Re: MOA base question, is there too much?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">You may be confusing which way you dial for longer ranges with which way the reticle moves.

</div></div>
I'm referring to which way the reticle moves, not the way the impact of bullet would move.

 

[Lindy]

Re: MOA base question, is there too much?

OK - no problem. I assume by now that your question of whether you can get too much elevation in the base has been answered.

 

[viav13]

Re: MOA base question, is there too much?

Oh yes, It has. Quite expertly i might add.

I've been browsing around on this site for over a couple of years now (off and on). Ive just recently added to the forum, my first i might add, to have some of my wonders addressed directly. I like to put in my .02 here or there also. Im always amazed at how much i learn or get retaught here.

Thanks for all the lessons.

 

[michaelt454]

Re: MOA base question, is there too much?

Just ordered the 30 MOA rail from Armalite, 80.00 plus shipping. I guess that was the easiest way around the problem, thanks for helping me out on that Lindy. Preshate ya!

Michael T.

 

[Lindy]

Re: MOA base question, is there too much?

Always glad to help an Aggie...