I was refering to Brownell's, though I did recant that statement. It appears some fit Andersons and some don't. I just picked up a603 / M16A1 upper on the ARFCOM Equipment exchange for $110 shipped tith port door, charging handle and teardrop FA. It had some minor corrosion on handle, and was ceracoated black, which is OK, because it is also going on an Anderson's.