Pretty much. As when the USAAF took the 75mm main gun from the M24 light tank of WWII and mounted it in the B25 [H-model, IIRC] twin-engine bomber, the Air Corps/Force concocts its own designations for things, GAU-this and GAU-that. [Gun, Aircraft Unit. It pays to have someone in the household who speaks USAF]
The barrel and workings of an M119 might work as well.