The Chicago Piano Gun appears to be based on the M1928 Navy Thompson submachine gun. It used 100 or 50 round drum magazines, along with 30 or 20 round "stick" magazines. It has the slowest rate of fire of any Thompson, at only 600 rounds per minute.
The Chicago Piano Gun is an older version of Thompson M1, with more firepower and much bigger ammunition capacity.
The weapon is a pre-order bonus for Gamestop PowerUp Rewards members who pre-ordered the game before April 30, 2011 (US and Canada), and for HMV pre-orders (UK). On May 31, 2011, the Chicago Piano Gun was made available as a free download for all game owners.
Official Description: "The Chicago Piano, used by both law enforcement officers and criminals, was favored for its reliability, ergonomics, compact size, large 45-round cartridge, and high rate of automatic fire. This bonus weapon will be stored in the trunk of Detective Cole Phelps' car throughout L.A. Noire, ensuring that extra firepower is always close at hand."
Despite being DLC, the gun can still be found at several points in game, mainly in the hands of Mickey Cohen's gangsters or Leland Monroe's gunmen. With the DLC, however, the player can find the gun in the trunk of a police car; the DLC simply adds the gun to the player's inventory.
- The name "Chicago Piano" was one of the nicknames for the M1921/M1928 Thompson submachine gun, a weapon which became infamous during the years of prohibition in the United States.
- The Chicago Piano has the highest ammunition capacity in the game as it features a 100 round Drum magazine. However, the ingame model shows it using a smaller 50 round drum magazine.
- In real life, many mobsters used M1921 or converted M1927 Thompsons, the latter being a civilian variant of the military M1928.
- The in-game model appears to be the same as the M1 Thompson with a drum magazine added; actual M1921/27/28 Thompsons had a forward pistol grip instead of a wooden forearm and a Cutts compensator on the muzzle to reduce recoil, and lacked the M1's distinctive "ears" alongside the rear sight.
- A very similar model of this gun was added to Grand Theft Auto V / Online in 2014, named the Gusenberg Sweeper
- ↑ The dlc.dlc7.big.pc file on the unencrypted PC version only took up 112 bytes of space, so it presumably contains a script or some file to add the gun to the player's car trunk, as the weapon was already present in the game's asset files.