Interesting. Yes, Dwight (and me and Don) have been interested in the Circle S, I do not believe it is for Simson.
The "S" that you see on a few luger magazines and on the toggles is more unusual than usual.
How often have you seen it on rifles and the like? To any collectors, if it is an "S", it must be Simson, but it could also be Suhl, Schmeisser, Saur, etc., although likely and thought of by collectors is for Simson, as it is seen on Simson ad's and triangle S.
In my fact finding, I try to use the geneology standard, prove it to me from at least two unrelated facts to prove anything

It is not always easy to do, but convinces me a lot more
Ed