Gat: short for Gatling Gun. I don't care what you call it, but calling your marker a "gat" seems wrong. The Gatling gun was a hand-crank-operated weapon with 6 barrels revolving around a central shaft. The cartridges were fed to the gun by gravity through a hopper mounted on the top of the gun. 6 cam-operated bolts alternately wedged, fired, and dropped the bullets, which were contained in steel chambers. Gatling used the 6 barrels to partially cool the gun during firing. Since the gun was capable of firing 600 rounds a minute, each barrel fired 100 rounds per minute.
These things were pretty damned big. Aside from being gravity fed there isn't much else similar. Maybe start calling all these high volume slingers Tommies instead? As in Thompson submachine gun, AKA The trench broom,the Tommy Gun, the Chicago Typwriter, the Chopper,Ukulele music, the Chicago Organ grinder.
Just a tought.