An an overview, a few years back (2001-2002?) I was quite excited when Armailte started selling their Eagle Arms version of the AR-10.  The main reason for my excitement was my plans to build an NRA Highpower match rifle but as seems to always be the case I had bigger dreams then my checkbook allowed!

About this same time, Knights Armament had started selling their SR-15 FF RAS tubes to the general public and I amaged to get my hands on a couple.  Well, to make a long story short, I did some looking and the SR-15 FF RAS will not work on the AR-10 and you can see the details on why here.  Well, after I finally figured out I couldn't use my SR-15 FF RAS on the AR-10 I next turned to my M5 RAS as I had read on Armalite.com's forums that these would work and I just had to try. 

In my endeavors, I found that the M5 RAS easily mounts on the AR-10A4 as long as you remove the clamp on the rear of the top RAS unit that would normally sit around the AR-15 gas tube and clamps into a groove in the AR-15's barrel nut. Removal of this clamp is necessary for two reasons as the AR-10's barrel has a larger chamber area that hits the clamp and prevents the two halves of the RAS from fitting inside of the snap ring PLUS the AR-10's barrel nut lacks the necessary groove that allows the clamp to grip the barrel nut. These two factors make this clamp sit too high for the RAS to fit an AR-10A4 upper. Once the clamp is removed via the small roll pin that holds the clamp in place, the M5 RAS fit like a champ.

The AR-10 looked great with the M5 RAS and the RAS was very solid even without the rear clamp. Anybody that has tried to remove AR-15 or AR-10 forend grips know just how solid the forend grips are held in place by the snap ring and this was adequate to keep the RAS mounted to my AR-10 for anything I wanted to do.  I had a few snapshots of my upper but the photos I had of my own rifle were not very impressive as I had planned to take better photos of it later but I ended up selling my upper and replacing it with an Eagle Arms AR-10T upper which is a whole other story now!

Just the same, following is a picture of another AR-10 with the M5 RAS mounted on it.  This photo was provided by SHIVAN of the AR15.com forums and is a much better photo then the ones I had taken of my own upper.