Jump pack troops can shoot with their weapons using their BS. All the normal rules apply so if the entire unit remains stationary they can use any rapid fire weapons they are carrying at full effect. Heavy weapons cannot be fired by moving jump packers, but may be fired if the unit is stationary.
Jump Pack Troops Shooting
Source: Core Rulebook 3E, p. 92
Jump pack troops shoot using their BS and can fire rapid fire weapons at full effect if the whole unit stays stationary, but cannot fire heavy weapons on the move.