A "Spit Weapon" is a selective-fire or automatic weapon that fires bursts of bullets. They come in a variety of calibers and magazine-capacities.
A Spit Carbine is a carbine or rifle that fires pistol or rifle ammunition. They are equivalent to Automatic Carbines, Battle Rifles, or Assault Rifles.
Spit Pistols are smaller weapons that are chambered for pistol rounds. They are equivalent to Personal Defense Weapons, Machine Pistols or Submachine Guns.
Spit Guns are larger weapons that have replaceable heavy barrels and feed from large drum magazines. They are equivalent to machineguns.
Spit Cannons are powerful single-shot or magazine-fed large-bore weapons fired from a prone or braced position. They are equivalent to Safari Guns or Anti-Materiel Rifles.
It is illegal for a citizen to own a functioning version of one of these weapons. Collectors are allowed to have models that have been deactivated by Justice Department armorers. Reactivating a weapon would require replacing or repairing most of the major parts and then finding and removing the tracking bugs built into it - a fruitless gesture.