| ||For an overview of Pulse rifles in the Fallout games, see Pulse rifle.|
While named similarly to the pulse grenade and pulse rifle prototype, it is not actually an electromagnetic pulse weapon, but instead shoots electrical pulses effective against all targets, not just electronic devices. This is the most powerful single-shot weapon you'll find in the game. However, its hitting power is offset by its relatively short range and low ammo capacity when compared to the likes of Gauss weapons. This gun is also less accurate than Gauss weapons due to the lack of ammo modifiers.
- This weapon may be found after gaining access to the Brotherhood of Steel bunker in San Francisco. It can be found in one of the lockers in the lower level.
- It may be found on random Enclave units, such as on the patrols around Navarro.
- It can also be found on robbers inside mountain caverns, in random encounters. These groups of robbers can be recognized because they are wearing combat armor.
- Scoring a killing blow on an enemy by either a critical, Bloody Mess trait or simply a powerful attack will turn the enemy into dust. While this is no trouble for opponents that have no inventory, it is a source of great annoyance when you try to loot an enemy. Since there is no longer a body, you have to pick up the items, which are scattered all over the ground, one by one. But you can go around this by turning the violence level down.
- The YK42B, unlike the YK32 pulse pistol, doesn't fire a visible purple projectile.
- Missing with this weapon can sometimes cause the game to crash, for instance in the basement of the oil tanker.