Low-mount optics on flat-top AR-15?

[Zak Smith]

A Rock River flat-top AR-15 followed me home today, and it needs some optics.

If I choose to go with an Aimpoint, can I just use a set of the

1. "Aimpoint 30mm Extra Wide Ring (for any "Picatinny" style mount), w/ thumb screw and slot", or the

2. "Aimpoint 30mm Extra Wide Ring, Light Weight (for any "Weaver" style mount)",

or do I really need the QRP mount and spacer?

thanks
Zak

 

[USMCsilver]

You are going to need some sort of spacer.

If you want to use the factory Aimpoint ring, you are going to have to get a GG&G F.I.R.E Rail. Either in "scout" lenth, or standard lenth.

Or, you can get an A.R.M.S. #39 (I think) Swan Sleeve.

Those two things just go over the flat top and give you some height.

Then you can mount your Aimpoint and your dot will be on the FSP.

Or, you can get a $195 GG&G Cantilever mount. That mounts the optics to the correct height and mounts it 2" forward or the last rail on the A3 flat top.

 

[Redlg155]

You can also go with the ARMS#22M68 w/spacer . $99 for the mount/ $7.50 for the spacer from Sable Co. This would cost you less than a Swan Sleeve and the Aimpoint mount together if you aren't really looking at a backup rear sight. If you decided to get a backup rear sight later the ARMS#40 would cost you $90. Of course there are other slightly less expensive options out there.

If you go with a Swan Sleeve such as the ARMS#38, they run $150 for the standard length. This comes with a flip up rear sight and you can just mount your aimpoint on the rail w/ the aimpoint mount and be in the correct position to co-witness with the iron sights.

I've used the ARMS mounts and was very satisfied with them. Either way with the standard Aimpoint mounts you would need some sort of spacer to get enough height.

Forgot to add..you can get just a standard sleeve for much less without the flip up rear sight.

Good Shooting
Red

 

[Zak Smith]

I know the spacers and/or sleeves are required to make the red dot colocate the front sight, but what about if there are no backup irons (for now)?

Without any spacer, will it just be "too low" to look through comfortably?

What about a low-power conventional scope, like a Leu 1.5-5X ? Do those also need a spacer, or will conventional rings work?

thanks
Zak

 

[Redlg155]

Without any spacer, will it just be "too low" to look through comfortably?

Yes. The AR15 has no drop at the stock. Conventional rifles and shotguns have a drop at the stock so that your head lines up naturally with the sights. With the AR design your head lines up naturally a couple of inches above the boreline, allowing you to comfortably look through the sights. If you mounted the aimpoint that low it would feel uncomfortable...at least for me it does. There are some folks out there who can shoot that way..but I'm not one of them.

The second obstacle is that your front sight will obscure the target with the aimpoint mounted that low. With a spacer your dot is right on the top of the front sight post when sighted in. If you don't have the spacer your dot lines up in the middle of the front sight base.


Good Shooting
RED

 

[Zak Smith]

What is the distance from top-of-flat-top to the center of the sight optics?

Two inches? 1.5?

-z

 

[Redlg155]

Dunno...I don't have one handy for me to measure. And again it will vary on what type of rings setup you are using. ARMS22M68 w/full or half spacer, Aimpoint w/Swan Sleeve, etc..

Giving the guys over at SWFA a call will help a bunch in finding the most economical way to setup the scope to suit your particular needs.

What about a low-power conventional scope, like a Leu 1.5-5X ? Do those also need a spacer, or will conventional rings work?

If you went to a conventional low powered scope you would most likely still need to go to either high or medium high rings depending on the objective bell diameter of the scope. If it is mounted too low the FSB will "ghost" in your field of view. No spacer would be needed, as the height of the rings will raise the scope up to the level needed.


Good Shooting
RED

 

[Airfix]

RRA has a "flat top riser base" listed for $35.

RED, that leads to another related question. If the flat top does not have any front sight installed, and if a person can place the head as close as the boreline, and assume the Aimpoint is mounted as low profile as possible, is there any after market front sight which is lower than the standard height available at all?

(Yes I know there will be problem to co-witness the backup rear flip-up sight.)

 

[Redlg155]

Don't know of one, but If I'm not mistaken the latest issue of GWLE has a "hybrid" AR that has low profile sights on it.

Another idea would be to have a gunsmith cut a dovetail in some mounts such as these from Bushmaster for the front and rear. Then you could mount adjustable sights or even some express type sights to your AR.

If you don't have one locally who could do the work you could always drop by AR15.com and ask Kurt over at the industries forum for a price. Everyone there seems to be very pleased with his work.

$14.95 for the mini risers from Bushmaster, $75 or so bucks for some tritium sights or AO, and probably 20 bucks to get the dovetails cut. That's not too bad price wise. If someone came out with an aftermarket product you could be it would be much more pricey.

Good Shooting
RED

 

[Airfix]

RED, that's a good idea, thanks. Shall give it a thought.

Also read that hybrid AR you mentioned, and noticed the front sight is definitely lower than regular ones. What more interested me is that RROC's choice operating sytstem, which seems to be very low maintenance. Surprise that the initial price is projected that high, but time will tell given the market responses.