They are sold by the Arms Dealer if either the Magnum, Lightning Hawk, or Elephant Killer are in the player's inventory.
- Crits scored when using Magnum Rounds will deal x2.5 damage instead of x2. As well as this, the knockback is increased by 50% as opposed to the normal 40%.
- As Magnum Rounds are hard to come by before Hardmode, it is wise to save them for boss fights.
- The Magnum's high base damage (and by extension the Lightning Hawk's and Elephant Killer's), paired with a well-timed activation of both Adrenaline and Rage, can easily allow the Magnum and its successors to deal massive damage, giving the player an opportunity to erase large chunks of boss health. This allows the player to get a lot of damage out of every Magnum Round.