A player looking to find a laser pistol early in the game may acquire two from the deli to the right of the cash registers at the Super Duper Mart. Both are in poor condition, so it is recommended to use one to repair the other.
If the player can find Vault 92, there is a AEP7 with several energy cells on a table just inside the entrance; aside from the perils of crossing the Wasteland to get there, this is entirely unguarded.
Another in decent condition pistol can be found in the Farragut West Metro Station tunnels, in a safe that is easily unlocked be a nearby terminal. This is easiest to find during the Following in His Footsteps quest.