Light-Fingers Hargrave

 refers to an unmarked quest in Fallout 3.

If you have the Child at Heart perk, you can convince James Hargrave in Rivet City to steal ammo for you. He will have ammo for you 12 hours after you talk to him for the first time and every 12 hours ever after. By either waiting or sleeping, one can simply get a infinite amount of ammo with enough patience.

Rewards

 * Ammo