To be honest, that title is rather tricky, and not just because I'm using the word "best" when only comparing two objects, rather than three or more. Know what I'm sayin'? Where my grammar trolls at?

Before I get into the RIS vs. RAS comparison, let me first specify the components of the two acronyms.

RIS = Rail Interface System
RAS = Rail Adapter System

There are actually quite a few variations of those two out there but after doing a bit of mild research on several major firearms manufacturer sites (e.g. Daniel Defense, Knight's Arm Co, etc), as well as a few other gun-related informational sites, I've determined that those are probably two of the more correct meanings. However, since there doesn't seem to be a standard definition that covers multiple manufactured rails, I'm not sure if there's a wrong answer either.

So what the heck is the difference between RIS and RAS then?

Find out after the jump...

KWA LM4 PTR, a gas blowback rifle, 9" Larue RIS, Elite Force Flip-Up Sights, Voodoo Tactical Matrix Pack
Airsoft photo by Tom Harris for the Pyramyd Airsoft Blog
When I first got the new KWA LM4 PTR, a gas blowback rifle, from Pyramyd Air, the first thing I wanted to do after test firing it was to get rid of that boring front handguard and put a sweet rail system on there.  Well, while I was extremely impressed with the accuracy of the LM4, I was extremely disappointed with how difficult it was to get the rail system on there, specifically getting the delta ring to screw all the way onto the threads of the LM4 upper.  The circumference of the threads on the LM4's upper was just a tad too large, partly due to the paint.

Click here to see how I resolved the issue after the jump...