Some could have a bolter, some could have all three, some could have just a bolt pistol and close combat weapon.
If you were to buy a plasma gun for one of the plague marines, then it would have to modeled.
Dark Angels 1750 win/loss Record
Win - 23 (Belial helped wreck Ryan's puny Eldar)
Loss - 13 (Brice's Necrons wiped me)
Draw - 2 (The 13th hold out in alpha take and hold)