A friend has one that is stamped R1 A1 Century Sporter with the older St. Albans address on the side of the lower. It does not have the thumbhole stock but has a truck bed spatter paint stock. It also has a bi-pod that does not seem to be a commercial Harris type ..it is kind of clunky. The finish on the bipod and all of the metal elsewhere is consistent. The selector has three positions with a pin that prevents the "A" being engaged. I did not see any broad arrows but he tells me that it is inch pattern. I am kind of lost about the early Century R1 A1's and did not see anything on this one marked Imbel. I will go back for a better look but need some more info on the early Century products. He is a reloader and shoots everything he owns and says this one functions just fine. The bore and crown look really good. I do know from some reading that the parts kits were well used with worn parts. Just wondering which countries parts kits were used by Century back then. He is asking $500 for this rifle with two mags.