Make Identifiable Criminal Rounds Obvious Act or the MICRO Act This bill amends the federal criminal code to require that certain semiautomatic pistols manufactured, imported, or sold by federal firearms licensees be capable of microstamping ammunition. A pistol is capable of microstamping if it can copy certain characters identifying the make, model, and serial number of the firearm onto the cartridge case of the ammunition. This rule only applies to semiautomatic pistols manufactured or imported into the United States after the date of enactment of this bill. The bill establishes fines for violation of the microstamping requirement. It shall also be unlawful to alter the microstamping capability of a firearm that has been transported in interstate or foreign commerce. Violators of this prohibition are subject to fines and suspension or revocation of any firearms license.