Actually, the Winchester designation was A5. Lyman bought the tooling and manufacturing rights to the A5 in 1928 and changed the name to 5A. The Winchester four point mounts remained the same. Lyman continued to manufacture the 5A until 1934, when the new Targetspot scopes were introduced, still using the Winchester type mounts. In 1937 the Junior Targetspot and Super Targetspot scopes were introduced, along with a new three point Fecker type rear mount and the indexing screws relocated to the right side.
All the above information taken from "Old Rifle Scopes" by Nick Strobel.
