I came across a photo posted by jontheturboguy P99QA Detail strip guide. In one of the pictures posted with his guide (linked below), there is some sort of wear on about 3/4 of the way to the rear portion of the black plastic rail on the right side of gun. I believe that this part is the Sear Group Assembly. It is almost directly above his first knuckle of the thumb. Can anyone tell me what that is? It is normal or indicative of wear? Thank you in advance for your insight and considerations. Herman.