The GB seller isselling on consignment and seems to be relying on the sellers description. I noted the comp and sight and he said that he asked the owner who replied "That's because it is a Navy model"
As for me, I picked up an M1A1 from Sienna as a pre-May and shot it yesterday. It works great. To tell you the truth, I much prefer the peep sight to the Lyman adjustable.
Be well, my friend.
Chappy