SOPMOD M4 Carbine
KAC Free Float RAS
KAC 2-Stage trigger
Knight's SR-47
Knight's SR-25K
M5 RAS on AR-10
AR-10 Rail FF Tube
M5 RAS Dissipater


Knights RIS and RAS Assemblies

The Modular Weapon System (MWS) is the generic term and military nomenclature for a series of quick attachment systems used to accommodate the use of various devices and accessories on firearm systems. The Modular Weapons System or MWS adds flexibility and adaptability to many proven rifle designs. The MWS uses use The MWS uses use MIL-STD-1913 "Picattinny" rails and meet military requirements for bore alignment retention and allows the rifle barrel to cool much faster than conventional hand guards.

The Modular Weapon System (MWS) was originally designed for the military M4 carbine as part of the U.S. Army Special Forces SOPMOD M4 Carbine (Special Operations Peculiar Modification) program. The concept has been expanded to include H&K rifles, submachine guns, shotguns and even handguns. The Modular Weapon System and the use of MIL-STD-1913 rails has allowed for the standardization of mounting systems used to attach various accessories to the base weapon system. The accessories that can be mounted to a MWS system such as: reflex sights, lasers, sling swivels, bipod, flashlights, and vertical pistol grips have greatly enhanced the tactical flexibility of the baseline weapon. The ability to customize each individual soldiers rifle for a specific mission and to integrate new targeting electronics, make this system a high priority for the U.S. Military and is providing elite military units and other users the versatility needed to postpone the obsolescence of current service weapons.

Knight's Manufacturing Company (KMC) has answered the Modular Weapon Systems (MWS) concept with a couple unique systems. The two most common are the Rail Interface System (RIS) and Rail Adapter System (RAS). Both of these units use MIL-STD-1913 and MIL-STD-1913 Update Notice 1 "Picattinny" rails incorporated into innovative forend rail assemblies to replace the factory handguards of the host SR-15(AR-15), M-16, and SR-25 weapon systems and provide attachment points for a variety of weapon system accessories.

The RIS and RAS units are similar in that they consist of two major components: a top component consisting of top, left, and right quadrants, and a bottom component consisting of a bottom quadrant. Each quadrant contains a MIL-STD-1913 rail that can be used to attach a variety of weapon accessories. Differences between these two units occur in the way that they attach to the handguard cap and delta ring/barrel nut, how the units are numbered, and the types of barrels that they can be used with.

Rail Interface System (RIS) (KAC P/N: 94297)

The RIS is the older version of the two systems and is numbered T-L-R-B (top- left-right-bottom) in odd numbers 1 - 13 beginning at the front sight and ending at the upper receiver. The RIS system works with a wide variety of barrel contours and mounts like a conventional handguard except for an adjustable metal tab, at the handguard cap, that squeezes the two halves together. At the rear, the RIS unit is held in place by the delta ring.

The biggest advantage with the RIS system is that it is able to accommodate a wide variety of barrel profiles while the disadvantage is that the RIS doesnít clamp to the weapon as solidly as the RAS system. Just the same, the Navy SEALS reportedly prefer the RIS over the RAS system for the advantages described above.

The Navy SEALSí solution in the future will be the Knight's free floating RAS, a one piece extrusion that I describe in great detail on the next page of this series. The FF RAS will allow the Navy SEALS to use a variety of barrel profiles including integrally suppressed weapons that is not possible with a standard RIS or RAS system in a new system that is much stronger then the RIS and RAS systems described here.

Rail Adapter System (RAS)

Knights M4 RAS (KAC P/N: 98064)

Knights M5 RAS (KAC P/N: 98065)

The R.A.S. system is the newer of the two systems and uses the same basic layout with a different system of attachment to the AR-15 and M-16. Knights manufacturing has a patent for the Rail Adapter Handguard System (US Patent# 5,826,363) and this patent contains an excellent description of their invention and the details about it. I also have scanned and converted my M5 RAS owners manual to a PDF file which you can see here (CLICK HERE).

The RAS system clamps to the handguard cap via a clip on the top half while the rear is attached by a clamping mechanism that fits over the M-16 gas tube and fits into a recess in the M-16ís barrel nut. This rear clamp is then tightened via a hex-head screw producing a very tight fit that prevents most movement as experienced in RIS units. The RAS also has a tighter profile at the front sight that limits the use of the RAS to barrels that measure 0.835" - 0.855" diameter just after the front sight tower.

The RAS is also different from the RIS is the way that they are numbered. The RAS units are numbered T-L-R-B 14 - 28 from the upper receiver forward. The Army and Marines use the RAS as it is sturdier for use with an M203 grenade launcher and other accessories that can be mounted to these units.

I should note that it is possible to use a M5 RAS on an Armalite AR-10 as well as on a Bushmaster Dissipator as described on the linked pages.


Home | SOPMOD M4 Carbine | KAC RIS and RAS | KAC Free Float RAS | KAC RAS II | KAC 2-Stage trigger | Knight's SR-47 | Knight's SR-25K | M5 RAS on AR-10 | AR-10 Rail FF Tube | M5 RAS Dissipater | KAC on EBAY

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This site was last updated 04/11/03