Lasgun

The lasgun basically fires blasts of heated laser bursts. The battery attached below the gun in front of the trigger guard. Each time the trigger is pulled, energy from the battery fires through a chamber of crystal lenses that focus the energy beam down the barrel exciting the energy further until it leaves it and hits a target. This superheated blast can be fired singly, semi automatic, or fully automatic. It causes a point on the target to be burned with the blast and ever so slightly irradiates it.

The lasgun was invented early in human history, well before the birth of the Imperium. It has been modified over time till the present day, where different patterns exist. These have been more cosmetic than anything and each hails from a specific Forge World blueprints.   Each lasgun is ubiquitous enough most ordinary citizens can tell what one is, and operate it relatively easily. It was originally created as am alternative to the autogun, allowing it to be used in place of the latter. This was done, as the autogun fires bullets called slugs, while the lasgun uses lasers, where it is easier to make the components for the lasgun instead of solid shot weapons, or transport the ammunition.   Before the Heresy, the Imperial Army used lasguns or at least the forerunners of them, and these replaced afterwards by more recent iterations afterwards. Now as a weapon it is a cheap reliable weapon most tied in with the Imperial Guard, and a good number of PDF (Planetary Defence Forces). The latter though, usually will have a mix or one type or another depending on local traditions or availability.

Lasguns are closely linked to the Imperial Guard, and so much so, it is the equivalent to a Space Marine and his Boltgun. So common is this weapon in many different areas of the Imperium & beyond, that it is seen almost as common amongst civilians as the autogun.