What is the significance of the size of the "S" on the forestock?
Printable View
A smaller S is seen on early Springfield stocks; a larger one of pre-WWI Rock Island M1903s. As a result, it is a prime way of identifying an early stock as to manufacturer. Many, if not most, were modified to later standards, but the S usually remained.
Nope - Springfield did not supply stocks to RIA. One interpretation of the S is "shortened".