The M5 used fixed ammunition, with the same 76.2x585R cartridge case – designated 3 inch Cartridge Case Mk IIM2 – as other descendants of the 3 inch M1918 anti-aircraft gun, and had basically the same barrel.
The M5 utilized standard ammunition, employing the same 76.2x585R cartridge case – identical to that used by other variants of the 3 inch M1918 anti-aircraft gun – and featured a comparable barrel.