The Model #9, Pro Thrower 1st appeared in the Randall catalog in it's 1948 publication. It is shaped differently than your example, being a more "slender" handle. Newer versions are more bulbous.
Bo had a couple made for his own personal practice, hobby, etc...in the late 1930's (38 or 39) according to Gaddis' book. Although I cannot (& I don't know if "anybody" can) "exact date" your example. my best "educated" (?) guess would be mid to late 1950's, considering your photos, etc.
Hope this helps...and "welcome aboard"!
Stay Sharp,
Capt. Chris