The Heavy Bolter issued to the Adeptus Astartes uses a larger calibre that their Standard Bolter, has a more powerful kicker charge gyro-jet. It is also fielded using the 'drum box' (see above). It has a slightly lower maximum rate of fire that the Standard Bolter, but due to the greater amounts ammo is more likely to actually be used in full auto (this leads many observers to conclude the Heavy Bolter is faster firing, but it is just the way they are used by marines). The Heavy Bolter is ideal for smashing strong points, buildings and light vehicles. Space Marines make good use of the to rapidly take out hardened positions within STC bunker complexes (Ecorium) or mow down hordes of xenos like 'nids.
There are no directly comparable weapons systems, but the easiest way to figure out it's power is to think of a Mk 19 automatic grenade launcher but using 60-80mm grenades with rocket motors instead of its 40mm. This gives each heavy bolt about ten times the mass of a real 40mm grenade. It can punch through most modern light armour vehicles with ease (kinda like an automatic RPG-7 but far more compact) and clear most rooms in residential buildings with one shot.
The Heavy Bolter is normally issued with modal Bolts much the same as the Standard Bolter. However there are variants that are sometimes employed is specific circumstances, such as single mode thermobaric Bolts. These variants are not common issue as Space Marines like to remain flexible, but some missions do allow for a certain level of predictability.
Thermobaric Bolts are effective against 'nids or Orks on 'paradise worlds', as well as renegade humans inside STC subterranean bunkers (where is consumes massive amounts of oxygen within the confines of the bunker). There are not so effective at penetrating fully armoured targets, or atmospheres/ areas with limited oxygen. totally ineffective in a vacuum.
Plasma Bolts to cut through almost anything, though ceramite armours offer some protection.
This is an update inserted into: Bolter info page
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