changed out a few things on mine...
Any permanent modifications to the rifle required?
Just took delivery of a MagPul MOE Fixed Carbine Stock from Brownells and installed it:
It’s rock solid.
I saw where you trimmed back the End Cap to eliminate the unsightly gap behind the receiver. However, in order to avoid shortening the length of pull any further, I chose not to do that and just live with the gap. It was also necessary to cut a notch in the bottom of the extension tube under-lug for the stock’s cross bolt to clear it (easily accomplished). Now, it’s good to go.