Knights RAS 7" Drop-In AR15/M4 Carbine Length Quad Rail

Knights Armament
(3 reviews)
Current Stock:

Knights RAS 7" Drop-In AR15/M4 Carbine Length Quad Rail


The Knights Armament M4 RAS (Rail Adapter System) was developed for use on US military M4 Carbines utilized a 14.5 or 16" barrel. With over 1 million rails issued to date, it is one of the most battle proven designs available for the AR15 platform. This handguard is a simple-to-install, drop-in upgrade that features genuine Mil-Spec M1913 Picatinny Rails along its entire length. What sets the M4 RAS apart from other 2-piece quad rails on the market is that it securely locks to the rifle’s barrel nut via a clamp and screw arrangement, making it a very solid foundation upon which to mount tactical accessories.

The KAC M4 RAS is a drop-in replacement part for standard, 2-piece polymer, M4-type handguards. The rifle must have a carbine length gas system, delta ring assembly, fixed front sight/gas block, and round handguard end cap. Lighter barrel profiles work best (M4 or Government contours). Heavier barrel contours may require modification to the inside of the rail. For AR15/SR15 based platforms only; not compatible with SR-25 variants.

Installation instructions are included.


  • Installs in minutes
  • Four MIL-STD Picatinny rails at 12, 3, 6, and 9 o'clock
  • Includes 3x Rail Protection Panels
  • Compatible with carbine length gas systems


  • Weight: 8.9 oz
  • Length: 6.25"
  • Machined from 6061/T651 Aircraft Grade Aluminum
  • Mil-Spec hard coat anodized


  • 5

    Posted by A random dude from OK on 15th Jul 2020

    I was on the search for the Knights Armament RAS M4 clam shell style quad rail to complete my M4 clone when it seemed like most other suppliers were on back order or out of stock completely. I stumbled upon Arms Unlimited by chance and I’m glad I did! Not only did they have the component I was looking for, they had it at $10 less average than the other “big box” websites, and offered expedited shipping at a reasonable price and time frame. Do I placed my order on a Monday afternoon at like 3pm CST, with 2-5 day shipping...I‘m expecting Saturday at the earliest I get my stuff...NO; my order is at my house waiting for me Wednesday evening! That was awesome! I’ll definitely shop from you guys in the future, thanks again!!

  • 5

    Posted by Standingkneelingprone on 14th Jul 2020

    BNIB as advertised

  • 5
    Ladies love the KAC

    Posted by BRAD on 23rd Jan 2020

    Awesome product, fits like a glove, sturdy, solid and will take a beating. Took me a minute to install it because I’m dense and I’m not a mechanical brain, I’m better at breaking shit and shooting shit. I’d buy another one. Not a free float rail.