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View Full Version : Help, please, with LaRue Tactical pivot mount for optics behind Aimpoint CompM4


ursavus.elemensis
08-16-07, 20:15
Question about mating an Aimpoint CompM4 red dot sight with a LaRue Tactical pivot mount for a magnifying optic:

Background:
I have a Bushmaster AR-15, M4A3. I have the Surefire quad rails. The top rail sits about an eighth of an inch below the rail on the top of the receiver of the rifle.

Question:
I got an Aimpoint CompM4 red dot site. See picture from their web site below. I wanted a magnification unit, so I bought the very cool LaRue Tactical pivot mount (http://stores.homestead.com/Laruetactical/Detail.bok?no=131) to ultimately be able to use the Aimpoint 3x magnifier, but temporarily I am using a 2.5x magnifying optic that LaRue is selling. Please note this is NOT a complaint or a question about that 2.5x optic.

This picture, from the LaRue Tactical website, shows the very cool LaRue pivot mount for optics. It is NOT a picture of my set up. It is a picture of a very well-made, very cool option for your AR.
http://stores.homestead.com/Laruetactical/catalog/pivani.gif

With the pivot mount just to the rear of the Aimpoint CompM4 sight, with both of them on the rail above the receiver, the center axis of the LaRue Tactical mount (and optic) is about a quarter inch above the optical center axis of the Aimpoint CompM4 red dot sight. Looking through the optic and sight moves the red dot up higher off the front iron sight of the rifle (without the optic, the red dot is right on the front iron site center post). This is a picture of my set up:
http://www.pafoa.org/forum/imagehosting/226246c4f5c950598.jpg

Moving the Aimpoint CompM4 to the top rail of the barrel (Surefire) moves the red dot another eighth of an inch down, and now the center axis of the LaRue Tactical optic mount is about 3/8 inch above the center axis of the red dot sight. Here's a picture of my set up:
http://www.pafoa.org/forum/imagehosting/226246c4f5c951cf1.jpg

WHAT CAN I DO ????
Suggestions appreciated
IrishDevil
08-16-07, 20:41
It looks like you need a riser for the Aimpoint to get them in line. The Larue flip mount will give a lower one-third witness, at least on my gun.
TWR
08-16-07, 20:41
I believe the swing away mount is designed to work with the Larue Aimpoint mount which is higher than the standard Aimpoint mount.

But I've been wrong before.
ursavus.elemensis
08-16-07, 20:48
It looks like you need a riser for the Aimpoint to get them in line. The Larue flip mount will give a lower one-third witness, at least on my gun.

I come to this forum to learn, and now I am in need of learning: What is meant by "The Larue flip mount will give a lower one-third witness"???

Also, by "riser" does that imply that some kind soul out there sells a product that I can use to raise up my Aimpoint CompM4 red dot sight? By three-eighths of an inch, perhaps? Without violating board policies and what not, can someone direct me to such a seller of such risers? Thanks in advance. Your chance to educate the willing learner is your chance to do a good deed for the day/night/etc. Thanks
IrishDevil
08-16-07, 21:00
I don't have any experience with the new Aimpoint. The flip mount is setup to match the Larue Aimpoint mount, which puts the front sight in lower portion of the sight. Larue makes a riser but it adds 5/8 inch to the height I believe. You have to find a way to get your aimpoint higher since the flip mount can't go lower. Only way I see that happening is the use of a riser. Unless there are alternative mounts for the 4.
Pinnacle
08-16-07, 21:09
I think the simplest answer would be for you to purchase the new Larue QD mount for your Comp M4 and call it done. I just saw a picture of it on TOS for the first time. I knew it was "on the list" but it appears that an announcement may be imminent.
TWR
08-16-07, 21:37
Sorry didn't notice it was a compM4 and I'm sure you knew the heigth difference.

However LaRue evidently makes the flip mount for an eo-tech as well, it allows you to mount the eo-tech without a riser and lines up. Might be just what you need. Call them and ask if it would line up with your M4, if it would I'm sure they would switch it out.

http://www.ar15.com/forums/topic.html?b=3&f=18&t=339125
kennytx
08-16-07, 21:59
Looks like you may need a LaRue mount for your Aimpoint to get both at the
same height.

E-mail LaRue Tactical and see if they have any suggestions.
FJB
08-17-07, 02:48
I've used the CompM4 with the LaRue Pivot Mount and an Aimpoint 3X Magnifier with no issues nor shift in POI. Aimpoints are parallax free so even as you view them through the Aimpoint 3x it won't make a difference. With the Aimpoint 3X the difference in elevation does not seem as pronounced. I'll attach photos at first chance.

S/F
UPSguy
08-17-07, 03:21
I know Mark answered a question I asked on TOS and there is a version of the flip mount that works with the stock M4.
SIMPLYDYNAMIC
09-02-07, 13:45
I've used the CompM4 with the LaRue Pivot Mount and an Aimpoint 3X Magnifier with no issues nor shift in POI. Aimpoints are parallax free so even as you view them through the Aimpoint 3x it won't make a difference. With the Aimpoint 3X the difference in elevation does not seem as pronounced. I'll attach photos at first chance.

S/F

Second what FJB said if you want to keep this variation but would advise the LaRue M4 mount as well.
AR-15A3
09-02-07, 20:15
I had a similar problem with my Aimpoint M2 on a low KAC straight mount that is a little lower than the LaRue pivot magnifier mount with the "poor boy" Hensoldt 2.5X magnifier, it doesn't line up but there's no problem with the function.

From the LaRue website about the LT659 (Tall, 1.725") Aimpoint M4 mount:

"The "Tall" mount aligns the CompM4 perfectly in front of the LT Pivot-Mounted Aimpoint 3XMagnifier."

If you would like it to match the height of the LaRue pivot magnifier mount you could get the LaRue M4 LT659 "Tall" model mount.

LaRue Tactical LT659 Aimpoint M4 QD Mount
Available in Three Heights:

LT659 (Tall 1.725") for standard AR15 / M16 / M4 uppers
LT659-NV (Medium 1.535") for absolute-cowitness and compatibility with USGI night vision mounts
LT659-HK (Short 1.395") for HK 416, and piston uppers.


Aimpoint Comp M4 w/ LaRue Tactical QD Mount website link (http://stores.homestead.com/Laruetactical/Detail.bok?no=159)
UPSguy
09-03-07, 00:14
I noticed this height difference when I mounted mine too. I was very pleasantly surprised to find out that it didn't cause any issues whatsoever when you sight the gun in. there is no POA/POI difference due to the offset heights.