Unlike the K9000 cyberdog gun, FIDO uses .44 Magnum rounds instead of .357 Magnum rounds, resulting in higher damage and a slightly higher spread. The brain case and the scope are red instead of green and the decal is changed to a bulldog. Other features of the K9000 cyberdog gun are included in FIDO.
The schematics for FIDO are located in X-8 research center, next to the terminal in the kennels, which can be accessed after acquiring the key. The key can be found in a security room off of the front lobby of the X-13 research facility. After acquiring the schematics, taking the K9000 cyberdog gun to any workbench will allow it to be upgraded into FIDO. The process requires a Guns skill of 75.