Giants manager Bruce Bochy told reporters that Bumgarner was "letting it go" during his 30-pitch session but said he still did not expect the left-hander to return to San Francisco's rotation until after the All-Star break.
Bumgarner also threw a 20-pitch bullpen session Friday and is expected to throw live batting practice at some point during the Giants' four-game series starting Thursday in Colorado against the Rockies.
The Giants plan to have Bumgarner make five minor league starts before rejoining their rotation, although the organization has not established a start date for the assignment.
Bumgarner has been sidelined since suffering a separated left shoulder and bruised ribs in a dirt bike accident on April 20. Ty Blach has filled in admirably for Bumgarner, going 4-3 with a 3.53 ERA in nine starts during the four-time All-Star's absence.