If the receiver looks light or uneven, it's probably dry. A light coat of oil on the anodized surface will cure the problem. The anodized surface of new ArmaLite rifles bears a matte finish. After repeated cleaning, the receiver assumes a semigloss finish quite similar to the early AR-10 rifles. The receivers and front sights are made of forgings.
Forging is a heavy industrial process that leaves small dents and dings on the forgings.
ArmaLite inspects all forgings for excessive marks or deformation, but no forging is free of them. This is a normal condition of forgings, not a defect. The AR-10 is normally equipped with a round edged buttplate for shooting comfort. The checkered buttplate is intended to protrude slightly from the plate to help the plate grip the shooter's shoulder.