Scope Mount for AR15 Flat Top

[Ironbarr]

I tried this elsewhere... not successful.

First - It seems to me that with the hundreds (thousands??) of scoped AR's, there'd be a reasonable "standard" setup for a modest optic system. I'm looking for riser/rings arrangement that will allow my scope to match the detachable carry handle iron sights configuration (2.6", or so above barrel center).

I have an older 4 X 32 scope - one inch tube - that I've used on a 3030. I want to mount it on an AR-15 flattop just high enough to match the irons' height and to clear front sight; it'll be my AR "beginner" scope. I've been looking hard for the proper riser (or whatever) for this purpose and I'm totally confused about size, model, material, etc. (so many variables). I tried Weaver rings without a riser but couldn't get past the front sight.

Oly Arms (my AR) has extra high rings for 30mm and inserts for 1" - http://olyarms.com/usa.html & click accessories... extra high is for scopes w/larger bells, but I prefer a riser so I can swap in the carry handle with red dot more easily.

I've seen some aluminum risers (cheaper) in less than 1" high. As I remember the irons are at 2.6+/- inches. Does that mean the scope center would be 1.6"? How does that work with a 1" tube math-wise?

Then there is the Picatinny/Weaver relationship - They don't fit each other, right? What do I need - a Picatinny-to-Weaver riser?

Confusing to me. Seems the world of optics is a whole thing unto itself.

There has to be a reasonably priced riser ring combination that provides a decent solution - I'd appreciate some advice and direction.

Thanks for your attention

-Andy

 

[Zak Smith]

I've only done this with Leupold rings, so bear with me.

I think you want about 1.4" +/- 0.1" from the top plane of the flat-top to the centerline axis of the scope. Add this to the approx 1.0 - 1.1" from the bore centerline to the flat-top and you get the original 2.6".

The first option is to get "super-high" rings that are about 1.4 - 1.5" from their contact to the top surface of the rail to the center line of the scope. An example of these are the Leupold MK4 Super-High rings. You will be limited in how far forward on the rail you can mount your scope (for eye relief) by the forward edge of the scope turrets.

The other option is to buy an ARMS or GG&G rail. This is a rail that mounts on top of the AR flat-top and provide a higher rail platform. They can be the same length as the AR flat-top, or extend forward. They add about 0.5" to the height of the rail. In this scenario, you probably want to use "medium" rings to mount the scope to the ARMS rail. The medium rings will be about 0.8 - 0.9" in height.

Alternatively, I think both Rock River and Armalite offer a 1-piece scope mount that clamps directly to your flat-top.

The other thing to think about is eye relief: for "full view" through the scope (no black tinges around the edge of the image), this is the distance from the rear lens to your eye. For example, if you mount a scope with 3" if eye relief with its rear even with the charging handle, your eye will have to be about 3" behind that. So if you shoot "nose to charging handle", it will be way too close. When I mounted a Leupold 1.5-5X with about 3.5 - 4.7" of eye relief, I had to put very far forward, so its rear lens was about 2" forward of the charging handle.



hope this helps
Zak

 

[Ironbarr]

Zak -

Thank you for your input. FYI, for the Oly Extra High rings I mentioned... A reply from Oly Arms today indicated that the rings, when attached to the flat top rail, would be a bit low but wouldn't be hampered by the front sight.

BTW: So I get the language right, is it "riser", "rail", or something else? I'd like to sound like I know something of what I'm talking about.

-Andy

 

[Zak Smith]

They are generally called "rails" or "SWAN Sleeves".

Here's the ARMS #36:

It comes in extended or super-extended length.

Here's the ARMS #38, which is the same, but with a built-in flip-up rear sight.

Here's GG&G's version of it:

Here's a picture of how I had my AR set up a while back:

(click for super-large version)

That's a Rock River flat-top AR-15 with an ARMS #36S-EX (super-extended) with Leupold Medium PRW rings (0.84" high, if I remember right) and the Leu 1.5-5X.

Hope this helps.

-z

 

[Ironbarr]

Zack...

That sure is a long rail. I read somewhere that there's a rig where two (military) scopes(??) were in tandom. Whatever it was, it must have used that rail, huh?

Truly appreciate your info. I see that there's a bit of space behind you in the pic. Shooting room, huh?

BTW - what are the two screws holding in the stock's butt area?

Thanks again.

-Andy

 

[Zak Smith]

Ironbarr,

Yeah, the rail I have is very long. The regular "extended" version is much shorter, only extending 1.5 - 2" forward instead of like 8 or whatever it is on mine. I got the super long one so the eye relief was right.

The two screws in the stock are for the adjustable "match" buttplate from Fulton Armory.

-z