Task: Question Generation
Input (English): Context : The Stoner 63, also known as the M63, XM22, XM23, XM207 or the Mk 23 Mod 0 machine gun, is an American modular weapons system designed by Eugene Stoner in the early 1960s. 
Subject : Stoner 63 
Relation : service entry
Output (English): In what year did Stoner 63 enter service?