Autocannon

An Autocannon is a type of rapid-firing, auto-loading direct-fire ballistic weapon, firing HEAP (High-Explosive Armor-Piercing) or kinetic rounds at targets in bursts. It is, basically, a giant "machine gun" that fires predominantly cased explosive shells though models fireing saboted high velocity kinetic energy penetrators or caseless ordnance do exist. Among the earliest tank/BattleMech scale weaponry produced, autocannons produce far less heat than energy weapons, but are considerably bulkier and dependent upon limited stores of ammunition.

Autocannons range in caliber from 20mm up to 120mm or larger and are loosly grouped according to their damage vs Armor. The exact same calibre of shell fired in a 100 shot burst to do 20 damage will have a shorter effective range than when fired in a 10 shot burst to do 2 damage due to recoil and other factors. Autocannon are grouped into the following loose damage classes:

• Autocannon/2
• Autocannon/5
• Autocannon/10
• Autocannon/20

Beyond the "standard" models, variants include the shotgun-like LBX and quick-firing Ultra and Rotary, and capital ship scale models also exist.

Calibre

Calibre is fluff for the size of the barrel that the shell or shells are fired from and no standard calibre has been set for any of the classes of Autocannon. Autocannon in a class vary by manufacturer and model, with the fluffed number of shells and calibre being specified, no Autocannon has been specified to be one shell fired for each "round" or burst of fire. Probable exceptions are the 185 mm ChemJet Gun Autocannon/20 mounted on the Demolisher combat vehicle and Monitor Surface vessel or the 203 mm Ultra Autocannon/20 on the Cauldron Born A BattleMech.

Barrel Arrangement

All Rotary Autocannon, some standard Autocannon, some Light Autocannon, and some Ultra Autocannon are multiple-barrel arrangements.