The lasgun is the most numerous weapon in the galaxy, the standard-issue rifle of the Emperor's countless human soldiers. It fires a focused bolt of laser energy that flash-burns flesh and punches through light armour, drawing its power from a replaceable cell that can be recharged in sunlight, over a fire, or from a vehicle's engine in the field.
Front-line troopers mock the lasgun as a flashlight, yet its virtues are exactly those the Imperium needs. It is simple, sturdy and almost impossible to break, and its ammunition can be improvised from almost any power source. A well-maintained lasgun will fire in the vacuum of space, the depths of the ocean, or the heart of a firestorm, and a soldier can drop one in mud, trample it, and still trust it to kill when he pulls the trigger.
Wielded in ones and twos it is unremarkable, but the Astra Militarum does not fight in ones and twos. A regiment's worth of lasguns firing as one becomes a wall of searing light, a disciplined storm of las-fire that no charge crosses unscathed. It is by this humble, unglamorous weapon, more than any grand relic or exotic gun, that the Imperium's endless wars are truly won — one massed volley at a time. It is a soldier's weapon in the truest sense, uncomplaining and always to hand, and the trooper who keeps his clean and his cell charged will seldom find it has let him down when the order to fire finally comes.