In the Happy Fun Quake Server, Pulse Rounds are used as Ammo for the Pulse Cannon. Beyond a difference in the name (the Shotgun and Double-Barrelled Shotgun no longer require ammo), they are identical to and replace Shells in the vanilla game. Note that Grunts drop 25 Nails in this modification, instead Pulse Rounds are supplied in Backpacks of 25 upon the death of an Enforcer.
As the Shotgun does not require Ammo, the player now starts a new game (or gets reset by Introduction) with 0 Pulse Rounds. Note that the player can also hold up to a maximum of 200 Pulse Rounds instead of the limit of 100 for Shells.