I may be kind of out of line here but since in the fluff the most common heavy weapon for a standard squad of 10 marines to have is the heavy bolter, so why not make it free with the purchase of a squad and then make it upgrade-able to plasma etc rather than making one marine's bolter upgradeable? Not only would it being free make it actually good but also things would be more realistic overall since not many chapters have squads that dont carry at least one special weapon.