Rick, one of my USMC snipers also has a completely unmarked stock (except for the drawing number in front of the rear swivel), if it wasn't for the "O" marking in the magazine cutoff. And just recently bought an exactly identical rifle with nearly pristine stock which has the same "O" in the cutoff and the D1536-4 at the rear sling swivel. Both have no other markings, like the P proof.