SANTA CLARA -- The 49ers appear to be mixing and matching along their offensive line as they search for their best combination.

After the second exhibition game, the 49ers closed practices to the local media. But based on video posted on the team’s official website, undrafted rookie guard Erik Magnuson saw some action Wednesday with the first-team offense for the first time this summer.

Magnuson, a 6-foot-6, 305-pounder from Michigan, is shown blocking on a play in which running back Carlos Hyde had a huge hole on a run play up the middle.

Starting tackles Joe Staley and Trent Brown were joined by veteran center Tim Barnes on the first-team offense, as seen on the video. Daniel Kilgore is considered, along with Staley and Brown, an offensive lineman virtually assured of being a starter.

Magnuson has been impressive in the 49ers’ first two-exhibition games while working with the backup units. Magnuson played the most of any 49ers offensive player (25 snaps) on Saturday against the Denver Broncos. He saw most of his action at right guard before moving to center for the team’s final four plays of the game.

The 49ers’ starting offensive line for the first two exhibition games has included Kilgore at center and guards Brandon Fusco and Zane Beadles. Other plays posted on the site show Beadles working with the first-team offense, too.

The 49ers do not appear comfortable with their starting guards while second-year player Joshua Garnett is out after undergoing a procedure to repair knee cartilage.