Engraving on the back of the watch case reads as follows:
JBJ
ROUGHRIDER
1966
Convex crystal, appears to be some type of plastic.
Appears to be the Accutron Calendar "C" model, based off the 1966 advertisement
Have doubled checked and found the 'C' variant to be correct. Variants A,B and D are similar, but it's all 100% a 1966 Bulova Accutron Calendar "C"

Great inscription, I wonder what it means. Thanks for sharing.
1966 Bulova Accutron Calendar "C"
looks to be a match.
1966 Accutron Calendar "C"
1966 Bulova Accutron Calendar "C". I found one reference of Roughriders from 1966 being a football team in Canada but the initials don't match anyone on the team.
In reply to 1966 Bulova Accutron… by JimDon5822
A good effort, Jim. Only reference I have seen relates to Teddy Roosevelt's command during the Spanish American War (1898). I think it's a pretty fair assumption that's not it......
In reply to 1966 Bulova Accutron… by JimDon5822
The initials were my grandfather's; John Bradley Jones. He got the nickname roughrider apparently by being a really mean tough guy.
In reply to The initials were my… by JoganLones
Heirloom watch! Very cool! That makes it a real treasure.
Shot in the dark here; did your Grandfather ride a motorcycle? The original Span Am Rough Riders were Cavalry.