The M1911 is weapon featured throughout the Thing-Thing series, as well as in the first Thing-Thing Arena game.
The doctor at the beginning fight 154 using this weapon. The doctor will drop the weapon when dead. Project 154 uses it to shoot out the overhead grate in his cell. He can also use it to kill the security guards. The M1911 is a relatively basic pistol, having a medium damage and a rather low rate of fire. It is not known if this is an M1911A1, due to the limited detail.
The M1911 returns and can be unlocked after the battle with Zeus in Hard Mode, along with an AMT AutoMag V. The player must gain 100 kills during the battle to obtain both guns. The M1911 has medium-high damage and unrealistically low recoil. Possibly an M1911A1, although the hammer spur is too small and cannot be seen in high enough detail to reliably verify.
In Thing-Thing 3, the 154 will start off the SV Infinity 1911. It deals decent damage but has a rather low rate of fire due to recoil. It's recommended to use the H&K SOCOM MK 23 instead once it is found, as it has the same damage but can be fired at a higher rate of fire due to lower recoil.
The 1911 Custom is 154's starting weapon. It has a laser sight attached to it.
In Thing-Thing 4, Project 154 will start the game with the 1911A1 and 50 ammo. It deals moderate damage and has decent accuracy, but a fairly low rate of fire due to recoil.
The 1911 Custom returns with slightly stronger shots than the 1911A1, but still has the issue of low rate of fire. It is depicted as a long slide pistol, as well. Unlike in Thing-Thing Arena, it has no laser sight. In fact, it looks almost completely different.