These rifles were built well before the "throw away" society we live in now came to exist. If a new stock had a minor defect in it, it wasn't thrown away but repaired and used anyhow. I have a beautiful 1945 Long Branch that has a large patch on the side of the butt where it attaches to the butt socket. Same thing, different patch. It was obviously done at the factory prior to assembly. If these rifles were coming down a commercial production line for civilian sales, what the OP states would probably be true but it isn't the case. They were military rifles intended for military use and produced by the thousands.