[@NecroKnight] Both actually. The one's from Cawls vaults (he has vaults all over the galaxy not just Mars) have been collected over the millenia. But it is possible for regular marines to be turned into primaris marines, i.e Marneus Calgar Because Guilliman has been in stasis he hasn't been able to countermand his original order to Cawl, So Cawl has just been building more and more vaults and shoving more and more primaris inside them for the last ten thousand years. Some are from the days following the Horus heresy and others are from various other points in time.