Rifle Scopes ar mounts, why so high?

[dferg77]

I see that all of the one piece mounts for ar's are around 1.5"
I understand that they are made to go over a buis but I dont really need one and it seems that 1.25" is about right for leupold 36mm, nightforce 32mm and other scopes. Regular rings work but the eye relief doesn't seem optimal especially for shooting prone. Is there any one piece options that I haven't been able to find? Thanks for any help

 

[pe5b]

Re: ar mounts, why so high?

NF has a 1.125 unimount with 20 moa built in.

 

[tt350z]

Re: ar mounts, why so high?

Most AR mounts are 1.5'' centerline because that's the height of the iron sights on a flat top. An example is an aimpoint with 1.5'' mounts, it'll allow true cowitness with the irons. Not because it has to fit over BUIS, there's a few BUIS that don't fit under the 1.5'' height.

The stock and barrel are inline. If you had low mounts on it you wouldn't be able to lower your head enough to be able to see through the optic.

As you can see once optics are mounted on a bolt rifle the height over bore is relatively similar (Most will say the cheek piece on the 700 is still to low, me included. Hence the reason why adjustable cheek pieces are popular).

If you can't get proper eye relief, move the scope/head fore/aft until you can get a good sight picture.

Height of a mount should not interfere with eye relief, only where your cheek weld is.

 

[Kells81]

Re: ar mounts, why so high?

If you don't understand why so high after seeing the illustration above you can learn the way I did. I picked up my first flat top AR several years ago and went for a scope. I mounted it just right with the bell just above the handguard. Well I soon figured out why they are so high when I couldn't get my eye low enough to get a decent look through the scope.

 

[sobrbiker883]

Re: ar mounts, why so high?

Actually 1.2ish is the height of irons above rail. 1.5 Aimpoint mounts furnish a "lower 1/3" cowitness with itons. Many scope's objectives may not clear using the 1.2 height.

The NF Unimount with AR's in mind is 1.3ish and the 1.125 NF is with boltguns in mind.

 

[tt350z]

Re: ar mounts, why so high?

I stand corrected.

I don't have any BUIS or FSB at all on my AR and the bobro is 1.5'' so that's all I know. I just assumed it was the exact height for absolute cowitness. I don't own an aimpoint so I just looked at Larue's site. Looks LT150 has a 1.7'' centerline for lower 1/3 cowitness and the LT152 is 1.2'' which should be absolute cowitness than. It doesn't appear that he makes any 1.5'' mounts for aimpoint anyway.

Hopefully the OP understands why AR mounts are typically taller than a bolt rifle mount.

 

[rjroberts]

Re: ar mounts, why so high?

Another issue is the ability to get the bell over the sight in the case of a scope with shorter eye relief. One needs to raise the scope more than one ordinarily would just to clear a standard sight. Yes, there are flip down sights to make that easier but, no matter how good, they seem "temporary" compared to the solid ones. I like using regular sights on an AR and a scope just for longer ranges, so I have standard height fixed (as opposed to flip down) sights on mine. Right now I am shopping around for a scope in the 4-6x range, and I intend for it to be over the top of the sights. Even though I'll possibly wind up with a 1-4x, the 1x will be the lesser used, intended for those times I happen to have the scope on. Most times, I use the irons with a Meprolight front.

 

[JRose]

Re: ar mounts, why so high?

Cheek weld.

 

[sobrbiker883]

Re: ar mounts, why so high?

hence the "BU" in BUIS.

 

[samnev]

Re: ar mounts, why so high?

I learned about the correct height required when i tried to mount an Aimpoint on a flat top without a riser. I had used Eotech's with out a problem so it came as asuprise to me when I couldn't get on the Aimpoint.