The .357 Magnum was first made available in the midst of the Great Depression so it saw few civilian sales. Being overly expensive at the time, it was used mostly by law enforcement and select mobsters looking for accuracy and high power from a hand gun.
The weapon has a capacity of 6 rounds and the player can carry an additional 6 reloading clips for a total of 42 rounds. It is the most powerful pistol in the game but it also has a high amount of recoil, giving it slower rate of fire. It occupies a slot in the right section of the weapons HUD along with other one handed weapons.
In all three Mafia II DLCs they're available for purchase at Giuseppe's, Harry's and McClusky & Son from the beginning.
You can find more real world information about revolvers on Wikipedia.
- When viewing the Magnum at Giuseppe's and McClusky & Son's it says "Feeling lucky?" beneath the name. This is a reference to Clint Eastwood's line in the 1971 film Dirty Harry.