With proper maintenance, I have had no problems with the M4 platform. Key words "With Proper Maintenance." The AR-15/M4 platform is one helluva weapon in everyway, but when I see what an AK can go through and still go boom I get a lil envious. What the AR needs is that AK/Glock reliability to go along with its modularity and accuracy.
I am trying to change that, or at least give myself the option of that extra reliability in some of the new Gas Piston AR's. Currently I am shooting a P.O.F. 415, LWRC, and the Bushy gas piston AR's. I also ordered a Sig 556 today. I am very pleased with my results so far, the P.O.F. chews up and spits out anything. I have yet to clean any of them aside from barrel break in, an they have all put about 2,000 rounds downrange with no problems. I expected this and much cleaner and cooler bolt action (which I got). I am still not sold just yet though because of the Gas-Piston system itself. While other parts run cooler and cleaner that piston and gas rod gets ULTRA HOT. Instead of somewhat equal distribution of heat, it takes the brunt... that's all fine and dandy because we all know that piston will withstand more abuse than the bolt will before rendering you combat innefective. BUT when it does blow and it comes to replacing one in the field that can be next to impossible, so I am gonna make damn sure I can make all that is gonna go wrong go wrong on the range first.
If anyone else has any input on Piston AR's (that owns one) I would lke to hear about it.