User blog comment:NecrusIV/Average age of a Space Marine/@comment-4608429-20120815184347/@comment-66.87.113.224-20120815185923

Where does it say that they cannot exceed 450? Canon limit is 1000 and thats crazy old. Marines are theoretically immortal, after a point they can age but remain physically perfect. In a Salamanders novel they found a salamander possibly as old as the Heresy. But he had waited so long he fused to his armor, but was not totally fine mentally. So marines may be extremely longer but being warriors usually and preferably die in battle.