One of the big unknowns for the 49ers going into this season concerned All-Pro defensive end Justin Smith.Would the 33-year-old be able to rehab from offseason surgery to repair a torn left triceps that limited his effectiveness last year?After one day of training camp, it appears the Niners have their answer. Smith should be just fine.In the team's opening day of full-squad practice, the four-time Pro Bowler – who anchors San Francisco's three-man front on the right side – looked like his old self.He was active, strong, full of energy and free of the brace he wore on his left arm through the postseason, when his effectiveness was diminished and the team's pass rush faltered.He said he's back to 100 percent strength again."I'm ready to go and it feels great," Smith told reporters Thursday.Justin Smith was one half of the team's Smith & Smith defensive duo that appears to be back at full strength for 2013. Right outside linebacker Aldon Smith, who plays behind Justin, was practicing Thursday, recovered from offseason surgery on a torn labrum."Some years you're going to have more injuries, some years you're going to have less injuries," Justin Smith told Cam Inman of...