The Ring, August 1955;
"Meeting for the third time in their short careers, Detroiters John Riggins and William Hunter put on a slugging bee before 967 fans at the MCA, for six solid rounds before Riggins was awarded a unanimous decision to run his undefeated streak to eight straight".
This bout fits with 1955, May 24 and gives Riggins 7 straight wins.
Query; If there was a third bout, when and where was it?
YT
