Unlock the Mosin Nagant Rifle in Metal Gear Solid 4:Guns of the Patriots for the PS3.
1. Access the Password Menu under Extras. This is only available after you beat the game once on any difficulty setting.
2. Enter mnsoymsyhn as the password.
The Mosin Nagant Rifle will be available when you load a saved game, or in a new game when you meet up with Metal Gear Mk. II.