What is the length and width of the m2 50cal machine gun?

A 50 calibre machine gun can have any length or width. The inside of the barrel is 1/2 inch. Gradually calibre as a gun size is being dropped in favor of metric. For example 9 mm is replacing 38 calibre. A 38 calibre pistol will shoot a 9 mm bullet. Mortars are now 61 mm instead of a calibre.