Rifle Scopes Correct mounting option

[bruchi]

Finished build on a "budget" 223 rig intended for long range shooting, around 300-600 yards, upper is a 24" bull barrel DPMS which has a raised rail for mounting optics as this:

I was under the impression that this added height be beneficial in making better use of the scope's elevation range of adjustment when it came to longer distances, as the use of a 20 MOA mount on a bolt action rig?

The scope I will be using is a Leupold Vari-X III 6.5 x 20 50mm which has a long eye relief so I was planning in using a LaRue mount designed to aid that issue, model SPR-E LT-139 but LaRue tells me my scope would then be to high and to use regular rings?

Buddy who is my AR mentor tells me to either get the regular 30mm Badger Ordnance rings or swap the upper for one with standard height rails and then get the LaRue mount?

 

[Rafael]

Re: Correct mounting option

Buying that upper to imitate an inclined base was a mistake.
A taller base is nothing like an inclined base, and actually increases the problem......but only a slight bit and only if your scope winds up higher than if you did not have the taller upper.
Now you are stuck with trying to find a mount that will give you 20MOA of inclination while not adding much height.

I am not familiar with such a base, but I am hopeful someone will chime in with an alternative.

 

[bruchi]

Re: Correct mounting option

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rafael</div><div class="ubbcode-body">Buying that upper to imitate an inclined base was a mistake.
A taller base is nothing like an inclined base, and actually increases the problem......but only a slight bit and only if your scope winds up higher than if you did not have the taller upper.
Now you are stuck with trying to find a mount that will give you 20MOA of inclination while not adding much height.

I am not familiar with such a base, but I am hopeful someone will chime in with an alternative. </div></div>

I clearly need some education here, I did not get the upper thinking it would do the same exact thing as an "inclined mount" but that it would help rather than make things worse for long range shooting, well at least to me 600 yards is so!

Got the thing mainly because someone let it go for a very good price and I was more attracted to it because of the bull barrel length of 24" and 1:8 twist to reach farther.

As I understood it this upper is a "Varminter type" one more prone to be used to shoot at longer distances?

So the first question is why does this upper has a raised rail what is the purpose of this?

I asked on another forum and was told that it was a "tactical" upper so a red dot, like an Eotech would end up at the correct height but this does not make a lot of sense to me?

Please set me straight here, this is by no means a "one of a kind" upper, someone ought to know what is the point to it!

 

[Rafael]

Re: Correct mounting option

I was hoping someone would speak up from a position of more experience with choices for this particular situation...since I have not had to deal with one like this before.

If the upper was not a high-rise upper, one could use a mount like this from Larue:
http://stores.homestead.com/Laruetactical/Detail.bok?no=42
That one includes 10MOA of incline to help get the most use from a scope with enough adjustment.
This type of mount is normally installed on a non high-rise upper to make the scope sit at the about the same height to coincide with a backup iron sight. Of course, this would make for a fairly high mount with your upper.

You could also try a set of Burris "zee" rings which use eccentric inserts to add inclination to the scope, recovering some of the "up" adjustment for longer range.

I am sure there are other choices as well, but I am not very familiar with them, as I stated earlier.

I looked up the Vari-X 3, 6.5-20X50 and it says it has 94MOA of adjustment. I did not see one with extended eye relief.
If this is correct, and you do not use an inclined solution, you will wind up with approximately 47MOA of elevation adjustment after you achieve your 100 yard zero. It may be less, or more, depending on many things and every rifle is a bit different....you just have to try it and see.

Question: Is 47MOA of "up" adjustment enough for the load and distance you intend to shoot?
If so, you can just get a set of standard rings or QD base and carry on. It has a lot to do with your load and the distance you want to shoot.

If not, then you need to find a base or rings that will add the inclination you desire to achieve the elevation adjustment you desire. If you install this on a 10MOA base you will get about 57MOA of "up" from this setup. Ring height is up to you...and how high you want the scope to sit...and the type of cheek you have on the stock.

I hope this helps you.

 

[LoneWolfUSMC]

Re: Correct mounting option

Buy a set of standard rings and drive on.

If for some reason you run out of elevation before you get to 600, then you need to get a high quality standard upper and go with an inclined mount such as the Nightforce Unimount or LaRue SPR.

I hope you got a sweet deal.

 

[brt1963]

Re: Correct mounting option

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bruchi</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rafael</div><div class="ubbcode-body">Buying that upper to imitate an inclined base was a mistake.
A taller base is nothing like an inclined base, and actually increases the problem......but only a slight bit and only if your scope winds up higher than if you did not have the taller upper.
Now you are stuck with trying to find a mount that will give you 20MOA of inclination while not adding much height.

I am not familiar with such a base, but I am hopeful someone will chime in with an alternative. </div></div>

I clearly need some education here, I did not get the upper thinking it would do the same exact thing as an "inclined mount" but that it would help rather than make things worse for long range shooting, well at least to me 600 yards is so!

Got the thing mainly because someone let it go for a very good price and I was more attracted to it because of the bull barrel length of 24" and 1:8 twist to reach farther.

As I understood it this upper is a "Varminter type" one more prone to be used to shoot at longer distances?

So the first question is why does this upper has a raised rail what is the purpose of this?

I asked on another forum and was told that it was a "tactical" upper so a red dot, like an Eotech would end up at the correct height but this does not make a lot of sense to me?

Please set me straight here, this is by no means a "one of a kind" upper, someone ought to know what is the point to it! </div></div>

The point of the elevated rail on an AR15 upper is to allow you to use normal, "low" rings and still have the scope high enough for a proper cheek weld. Standard AR irons are 1.4" above the upper, so with a normal flattop, you'd use the "ultra high" rings to get the scope at the right height. The one you have adds ~0.5" of elevation, and standard "low" rings are 0.9" - getting to the magic 1.4"...

 

[bruchi]

Re: Correct mounting option

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: feersum dreadnot</div><div class="ubbcode-body">
The point of the elevated rail on an AR15 upper is to allow you to use normal, "low" rings and still have the scope high enough for a proper cheek weld. Standard AR irons are 1.4" above the upper, so with a normal flattop, you'd use the "ultra high" rings to get the scope at the right height. The one you have adds ~0.5" of elevation, and standard "low" rings are 0.9" - getting to the magic 1.4"... </div></div>

Thanks, that clears a lot!