Heavy machine guns represent a large family of air- or water-cooled projectile weapons that are usually fed with belts of linked ammunition. HMGs require a vehicle mounting or emplaced firing position for effective results. An HMG magazine contains enough ammunition for 10 rounds of firing, but each round of firing eats 25 credits worth of projectile ammunition.
Some weapons are simply too big to be comfortably used without a tripod, fixed support, or vehicle mounting. Others require specialized training in the use of heavy munitions.
Heavy machine guns consume large amounts of standard ammunition.
Some heavy guns can be fired to suppress. Double the usual ammunition is fired in one round, and every target in front of the weapon that is not under hard cover is automatically hit for half normal damage. A successful Evasion saving throw eliminates this damage.
When firing at TL4 military vehicles such as gravtanks, mechs, or starship armor, most TL3 Heavy weapons don’t count as Heavy for armor-penetrating purposes. Demo charges and explosives do, however.