I am considering getting the KAS RAS sytem for a Bushmaster A2 M4.  Everything I read indicates it mounts at the rear to the barrel nut.  How difficult is the installation?

Thanks,
OH58D

Here is a short article I wrote on the MWS a few years back. It will answer your question.

Knight’s Armament Company Rail Interface System
KAC P/N 94297.

“The design stems from a requirement for a universal mounting platform that lends itself to a variety of weapons. It’s unique design facilitates it’s 4 rails for the addition of other weapons, primary and secondary sights, visible and IR lasers/ pointers, grips, sling swivels and cover grip panels allow it to give new life to older weapon designs. The Modular Weapon System is what Knight’s calls their product line. This includes the AR15 / M16 family and the Heckler and Koch series. The Rail Interface System, P/N 94297 and the Rail Accessory System, P/N 98064 are the carbine versions that are beginning to be found on AR15’s for their distinctive features.

The basic design of the rifle and carbine MWS is a top / side section that is shaped like a “U”.  This section has three of the four rails.  The lower section has the aluminum heat shield and last / lower rail. The 4 rails are protected by cover panels that come in various lengths to allow protection from the elements and surrounding’s.  KAC recommends a cover panel be in place if nothing is mounted on that rail. Construction of the MWS is of aircraft grade aluminum. It is an extremely strong structure.  

The RIS attaches to the weapon by clamping to the front handguard cap. The screw on the top / front of the RIS must protrude above the rail surface. The screw is threaded through a latch that acts like a clamp when tightened. After removing the standard top and bottom handguards from the weapon the front section of the RIS is placed into the HG cap. Pulling back on the Delta ring allows the rear section of the RIS to engage the barrel nut. On the RIS are two pins that interface with the scalloped sections on the barrel nut. These pins ensure there is no rotational movement and help retain the zero of accessories. After the Delta ring is allowed to engage and lock the rear section in place the front screw / latch can be tightened. Tighten the screw enough so that there is adequate pressure on the latch but not enough to deform the front HG cap. This will help in maintaining the zero of the MWS.

On a side note, the RIS attaches by clamping / latching onto the front handguard cap. The RAS attaches by clamping / latching onto the barrel nut. This was done as a requirement from the US Army. Both types are currently being issued to our military.

The bottom / lower section installs in a similar fashion as the upper section. Insert the front section into the HG cap and compress the Delta ring allowing the lower section to pivot into place around the barrel nut. Releasing the Delta ring now clamps the MWS in place. Tolerances are tight so they ensure stability. Once you have the 2 pieces in place you can install the outer ribbed covers.
These sections act like handguards. The carbine sizes are 11 rib, 6 rib, 4 rib and 2 rib. KAC recommends you always have the covers on an unused rail for the rail and shooters protection. I cut down one of my 11 section rib to a 9 section because that is the length I needed which means you can tailor these to fit your custom requirements. They slide on the rail and stay in place via a spring-loaded clip.

A more versatile mount I have yet to find. The units I have all sit on my M4 copies and give an added structure to this weapon like nothing else. They are worth every penny spent. When combined with a KAC Forward Handgrip, P/N 95122, and the red dot of your liking this setup gives you steadiness and balance to aid in target acquisition and proper shot placement. The side mounted sling adapter is another great addition for carry and blends well with the above setup.
The MWS is built for Soldiers and battle. Its design enhances the civilian AR15 by giving it "Modularity". For someone like myself it allows a new facet to the many roles our AR15 plays in our shooting sport. “

JohnM,

Thanks for the article.  Very informative!!
Regards,
OH58D

User installation is easy.
RIS, you need a flat blade screw driver and about 30 seconds.
RAS, you need a 1/8" allen wrench and 30 seconds.
It will take you longer to read the instructions that perform the installation.
So simple, but so secure...
ColdBlue sends...

[i]"It will take you longer to read the instructions that perform the installation."[/i]

Hahaha! So true!