This rifle appears in Fallout, Fallout 2 and Fallout Tactics. In Fallout 3, it was replaced by the Enclave plasma rifle, and is only mentioned by Owyn Lyons. However, it makes a return appearance in Fallout: New Vegas in its original form.
The game takes place in the year 2161 on the West Coast of what used to be the United States of America, particularly in California. It begins in Vault 13, the protagonist's home. Vault 13's water chip, a computer chip responsible for the water recycling and pumping machinery, has broken. Armed with a PIPBoy 2000 and meager equipment, the protagonist is sent out into the remains of California to find another water chip.