I just bought a new remington 870 express 12 gauge with a 28 inch barrel. I was wondering on how to check the gun for any quality issues. I heard that the magazine spring retainer and the trigger plate assembly were made of plastic, so should I buy new metal parts for the gun? Or should I just leave it alone, and just assume that the gun was made with no problems. Does any of the "differences" between the express and the wingmaster matter? Do things like the rougher unpolished finish and burrs matter? What about the MIM issue and the "dimples?"