Originally Posted by billt
Remember of the guns you mentioned, LWRC weapons are piston operated, while BCM and Larue are direct impingement guns. I currently shoot 2 LWRC rifles, and both are exceptional guns. If you're going to go piston I would rank LWRC at or near the top. They are also expensive. Piston guns clean up much easier because you don't have a weapon that $h!ts where it eats, so to speak. If that's important to you, only you can decide. I find myself shooting my LWRC guns more because of this. The less time I have to spend cleaning after a lengthly range session with AR's, the better. If I ever purchased any more AR-15 rifles, they would be piston. Most likely I would try an LMT piston gun in .308.
Bills right the piston guns are just easier to clean and run cleaner , they both have their advantages and disadvantages , Piston is a little heavier yet easier to clean , I hear its big advantage is for full auto use.
DI guns are a little lighter , yet like Bill said they are dirtier in the upper and lower because of the pukeage they produce but thats not a big deal as long as you keep them clean .
All 3 are great guns you just have to choose yourself . Pick them up , hold and fondle them. Pull the trigger and see if there is one you like better than the other . Have a idea of what you want when you go in . Some dealers will direct you to the gun they make the most money off of some dont ,Just depends on your dealer .