Shadow,
In previous experience, I learned that the FN/FAL really preferred that you let it kick hard. In other words, go back to a standard issue buffer, springs, etc. Also, while the magazines look indestructible, they are relatively finicky. Oh yeah, no matter how many untrained revolutionaries you see carrying one covered in mud, this weapon likes to be CLEAN. That is unless it is between "broke-in and worn-out".

Good Luck