Shot 300 rounds yesterday through my new colt.  Function was flawless!  This model has more recoil than my 6400c, indicating that the muzzle brake on that gun is somewhat effective.  I had an ARMS flip up sight that came loose during the session...FYI use locktite on that thing.  

Once I got my aimpoint dialed in it was good to go.  

Upon cleaning, I noticed that the anodizing has worn off the feed ramps in the barrel extension and was now polished bare metal.  The wear was not in the aluminum part of the upper reciever (so-called m4 feed ramps) but in the steel barrel extension notches.   I have never seen such wear before in my match targets which have seen more use.   Is this normal?


BTW, I had an ATF letter in my car to protect against overzealous cops, though no one asked.