Ol' Painless (Fallout 3)

Ol' Painless is a slightly more powerful .32 Hunting Rifle.

Characteristics
Ol' Painless does slightly more damage per shot, has a slightly faster rate of fire, reloads slightly faster than the regular Hunting Rifle, and also has a good durability and can be repaired with ordinary Hunting Rifles. Ol'Painless is one of the few weapons with 0 spread, meaning non-VATS shots go exactly where you aim them.

Location(s)

 * In an unpickable safe in The Republic of Dave Capitol Building. Dave's special key required to open the safe.
 * You can get the key by pickpocketing Dave.
 * You can also get the safe open by successfully electing another member of the family. When Bob is elected he would say he needs to throw out Dave's junk. If Rosie is elected, she would give you Dave's items as your "reward" for helping her. Even so taking from the safe is still considered stealing (Likely a bug). If you take Ol' Painless from the safe and then speak to someone from the town, it is possible they will take it from you. If this occurs the only way to get it back is through more negative karma of either pickpocketing it or killing them and looting it.
 * You can obtain the key if you have the "You Gotta Shoot 'Em in the Head" quest as well. Through speech checks, Dave gives you his keys as an item to show Mister Crowley that he is dead, when in fact he is alive. This key can be used to unlock his safe containing Ol' Painless. To avoid getting caught stealing, either use a stealth boy or tell everyone in town to vote in order to make him move out of the room to check the ballet box.
 * If you chose to kill Dave, you will be attacked by both of his wives (FYI: he's a polygamist). Also note that it is possible that the other residents of Republic of Dave may be unaware of your killing Dave and his wives, and thus letting you escape mass Bad Karma Carnage.  Another option is to declare war on the Republic and everyone will turn hostile then you can kill them with no Karma loss.
 * Occurrence of Ol' Painless in the locked unpickable chest (Muddy Rudder Supplies) inside Muddy Rudder bar in Rivet City is a random event. Belle Bonny's Key (carried by none else than Belle Bonny) is required to open the chest, the key cannot be pick-pocketed.

YouTube Videos
Obtaining Ol' Painless 3jzjR7YyoG4