Rifle Scopes Is 5 MOA enough to zero at 100 yds?

[aerochris]

Hi everyone. I have a Howa 1500 Varminter in .308. It has a 20 MOA base. I purchased a Burris Tac30 6.5x-20x-50 optic. The problem is, this particular Tac30 only has 50 MOA total adjustment.

I expect 50 MOA total will give me 25 MOA up and 25 MOA down. Then when you factor in the 20 MOA base, I should end up with 5 MOA of adjustment to get to zero.

Do you think 5 MOA is enough adjusment to zero at 100 yards? If not, I feel like I need to return this scope and not mount it. But if it will work, I am happy to keep the scope.

Any ideas?

Thanks,

Chris

 

[J.A. Hamilton]

Re: Is 5 MOA enough to zero at 100 yds?

Only one way to find out for sure, but I would say it is cutting it pretty close.

Josh

 

[Brasscow]

Re: Is 5 MOA enough to zero at 100 yds?

Chris,

There is natural error in the manufacturing of the rifle, base, rings, and scope. 5MOA may or may not work. Theoretically it will... at least for elevation. Don't forget that at the extreme ends of elevation your windage is drastically reduced as well. I hope that base and rings run true with your barrel, because if you get the elevation you won't have a whole lot of windage adjustment left.

Best of luck!

 

[JFComfort]

Re: Is 5 MOA enough to zero at 100 yds?

Wait, wait. If you zero @ 100 yards and you have 25 MOA elevation from your zero then the 20 MOA base should give you a total of 45 MOA which is enough to get you out to 1000 yards just fine. Make sure your base if canting the scope downward in the front.

That's how I've always understood it, now you may not get exactly 45 MOA of elevation but it should be in that ball park.

 

[ORD]

Re: Is 5 MOA enough to zero at 100 yds?

It will work fine.

FWIW, everything I have read on the Tac30 scopes shows that the actual internal adjustment range is 50" @ 100yds, which technically isn't exactly 50MOA (but it is VERY darn close for all practical purposes).

 

[JFComfort]

Re: Is 5 MOA enough to zero at 100 yds?

1 MOA = 1.047" @ 100 yards

 

[gugubica]

Re: Is 5 MOA enough to zero at 100 yds?

I would not be comfortable with that. even IF you can get it zeroed, you will basically have NO windage adustment at 100. That may not be a big deal, but at 200 and 300, you will have very little.

As said before, it may work, it may not. If just depends on which side of the theororetical mechanical center you wind up on.

 

[gugubica]

Re: Is 5 MOA enough to zero at 100 yds?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JFComfort</div><div class="ubbcode-body">1 MOA = 1.047" @ 100 yards </div></div>

Correct, so if it gives you 50" at 100, you actually have LESS than 50 MOA.

 

[kombar]

Re: Is 5 MOA enough to zero at 100 yds?

Just because the down adjustment might be limited doesn't mean that the windage will be limited by the same amount. If there's only 5 MOA of down available, then there will be a total of 30 MOA of windage.

Except the other thing is that there will probably be more than 5 MOA of down available, since some up will need to be used to get to a 100 yard zero in the first place. It's impossible to say of course, since as others have already said, tolerances between the rifle, base, rings and scope can stack and who knows where it will really end up.

I'd say run it, chances are it will work fine.

 

[gugubica]

Re: Is 5 MOA enough to zero at 100 yds?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kombar</div><div class="ubbcode-body">Just because the down adjustment might be limited doesn't mean that the windage will be limited by the same amount. If there's only 5 MOA of down available, then there will be a total of 30 MOA of windage.</div></div>

Wrong, if you have your elevation close to its extents, you lose windage adjustment. In the pic below, Line A is ideal, it is mecanically centered, you have the most available travel in both directions. Lines B and C are less than ideal. You have much less travel available for windage adjustment (right to left). Lines B and C are shorter than A due to the limits of the tube at the edges.

 

[ChadTRG42]

Re: Is 5 MOA enough to zero at 100 yds?

^^^^ The A, B, C chart is correct. It will reduce your windage when the elevation is at/near the bottom of the adjustment.

 

[Aries64]

Re: Is 5 MOA enough to zero at 100 yds?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gugubica</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kombar</div><div class="ubbcode-body">Just because the down adjustment might be limited doesn't mean that the windage will be limited by the same amount. If there's only 5 MOA of down available, then there will be a total of 30 MOA of windage.</div></div>

Wrong, if you have your elevation close to its extents, you lose windage adjustment. In the pic below, Line A is ideal, it is mecanically centered, you have the most available travel in both directions. Lines B and C are less than ideal. You have much less travel available for windage adjustment (right to left). Lines B and C are shorter than A due to the limits of the tube at the edges.

</div></div>
Exactly correct, <span style="font-weight: bold"><span style="font-style: italic">gugubica</span></span>.

Keith

 

[aerochris]

Re: Is 5 MOA enough to zero at 100 yds?

Thanks a lot for the replies everyone. I guess I better send this optic back. What in the world were they thinking having only 50 inches of adjustment in this very nice scope?

 

[One-Eyed Jack]

Re: Is 5 MOA enough to zero at 100 yds?

Yes, 5 MOA is enough for a 100 yard zero.

But, your scope may not have 25 MOA up and 25 MOA down, or even 50 MOA total travel. While those may be the numbers on paper, every scope can be a little different.

Finally, if your scope's erector is at the bottom of the tube at the 100-yard zero, it may have little or no windage adjustment. So, you might not be able to zero it in the windage direction.

Hope it works!

 

[kombar]

Re: Is 5 MOA enough to zero at 100 yds?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gugubica</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kombar</div><div class="ubbcode-body">Just because the down adjustment might be limited doesn't mean that the windage will be limited by the same amount. If there's only 5 MOA of down available, then there will be a total of 30 MOA of windage.</div></div>
Wrong, if you have your elevation close to its extents, you lose windage adjustment.</div></div> I never said you didn't lose windage at the elevation extremes, I said windage wouldn't be limited by the same amount. What I meant by that was if you only have 5 MOA of elevation left, in this case 10% of the total travel, your available windage wouldn't also be limited to 10%.

I was responding to your claim that: <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gugubica</div><div class="ubbcode-body">you will basically have NO windage adustment at 100. That may not be a big deal, but at 200 and 300, you will have very little.</div></div> The numbers I gave were calculated values, which is why I said there would be 30 MOA available, and not the maximum of 50. In this case, that's 60% of the total windage travel at 100 yards, even though it's very near the extremes of elevation. At 200 and 300 yards, there would be about 70% and 80% of the maximum windage travel, and those are the figures before including the elevation required to zero at 100 yards.

If everything was perfect, you would get the maximum windage adjustment somewhere around 600-700 yards if using a 20 MOA base. Of course, as One-Eyed Jack points out, things don't always work out that way.