The biggest upgrade to the M2 was the transition to the M2A1 model in the 2000s. The standard model for most purposes was the M2HB, an air cooled version with a heavy barrel.

Refinements made to the new design reduced weight by switching from a water- to air-cooled barrel. The resulting design is what is now easily recognized as the M2 Browning Machine Gun.

The M2 .50 cal machine gun is ... This upgraded version includes such enhancements as a quick change barrel ... headspace and timing must be set after assembly and prior to use. In the M2, ...

The original M2 "Ma Deuce" .50 Caliber Machine Gun is a belt-fed, ... after assembly and after required barrel changes when the barrel becomes extremely hot from high volumes of fire.