After five albums in 15 years, Alter Bridge quickly exited nervy adolescence (remember “Metalingus”?) and has comfortably matured. Their sixth album Walk the Sky shows their updated priorities, from banging heads to moving hearts. Yes, the curling, snarling guitars that permeate “Native Son,” “Pay No Mind,” and “Wouldn’t You Rather” speak to their sharpened metal pedigree. But it’s singer Myles Kennedy and lead guitarist Mark Tremonti’s melodious thunderstorm that is both crushing and refreshing; songs like “Godspeed,” “Forever Falling,” and the album closer “Dying Light” firmly secure their place in the melodic hard rock universe.