Mort Weisinger retired from DC in 1970 and his final issue of "Action Comics" was issue #392 (September 1970). Murray Boltinoff became the title's editor until issue #418. Metamorpho was the backup feature in issues #413–418 after which the character had a brief run as the backup in "World's Finest Comics". Julius Schwartz became the editor of the series with issue #419 (December 1972) which also introduced the Human Target by Len Wein and Carmine Infantino in the backup feature.The Green Arrow and the Black Canary became a backup feature in #421 and ran through #458, initially rotating with the Human Target and the Atom. Between issues #423 (April 1973) and #424 (June 1973), the series jumped ahead by one month due to DC's decision to change the cover dates of its publishing line.