SANTA CLARA Add Joe Staley and Frank Gore to the long list of 49ers starters who are sitting out spring practices recovering from offseason injuries.
Staley had arthroscopic knee surgery after the season, while Gore's ailment is more of a mystery.
"Just working through something," 49ers coach Jim Harbaugh said Tuesday. "Nothing too serious."
Staley dealt with his knee issue during the 2012 season and could have played through it again this year but decided to have the procedure.
The 49ers are looking for a swing offensive tackle, and Staley's absence is allowing more time to evaluate Kenny Wiggins, who played at Elk Grove High School, rookie Carter Bykowski and Adam Snyder.
Starting right tackle Anthony Davis did not attend Tuesday's voluntary session, and the de facto starting tackles were Wiggins on the left side and Snyder on the right.
Other veterans who sat out or rehabilitated with trainers included defensive end Justin Smith (arm), outside linebacker Aldon Smith (shoulder), outside linebacker Ahmad Brooks (unknown injury), guard Mike Iupati (shoulder) and wide receiver Mario Manningham (knee).
Three other starters, cornerback Tarell Brown, linebacker NaVorro Bowman and center Jonathan Goodwin, did not attend the session. Receiver Michael Crabtree is recovering from last week's surgery on his torn Achilles' tendon.
The good news for the 49ers: Receiver Kyle Williams (knee) and running back Kendall Hunter (Achilles') were in uniform and participating in individual drills at the start of practice. Williams said he intends to be ready for full practices at the start of training camp in late July, and Hunter appears to be on the same track.
Et cetera The 49ers had a big group taking turns at punt returner that included running back LaMichael James, receivers Quinton Patton, Ricardo Lockette and Chad Hall, quarterback B.J. Daniels and cornerback Perrish Cox.
James said his goal this offseason was to gain strength and explosion. He's up to 205 pounds after playing at 195 last season.
Receiver Marlon Moore, who played at Natomas High, stood out at times. He has good size and downfield speed, and his value as a special-teams gunner might improve his chances when coaches are making final cuts.