I installed the Enidine buffers in 2 of my AR's. An M4 and a CAR. They made a noticeable improvement, and smoothed things out. A good friend of mine told me I was nuts and that they were junk, but I got them from Brownells, so no concerns.
Then he shot my rifles and was blown away. They also really helped with "bolt bounce".
I'll end up putting them into the rest of my rifles eventually.
But my experience was all in 5.56.