So you know the laser that sentries fire and the one that the Roarmulus Twins fire? This will work similarly to that.

Acquisition

The 2 Star Lasergun can be obtained for 15 Bark Modules at Brinks.
The 3 Star, 4 Star, and 5 Star recipes can be found at Basil.

How It Works

The Lasergun lines has a 2 shot magazine, it fires a laser straight ahead which goes 7 tiles before dying out. The bullet pierces through ALL enemies in its path. Hitting them all for damage. The charge attack fires a laser which keeps going until it hits a wall, allowing you to snipe enemies, it also does more damage.

Weapon Lines

Elemental Shock:
2 Star: Lasergun
3 Star: Electric Lasergun
4 Star: Jolting Lasergun
5 Star: Power Surge

Pure Piercing:
2 Star: Lasergun
3 Star: Precise Lasergun
4 Star: Penetrating Lasergun
5 Star: Laser Drill

Elemental Fire:
2 Star: Lasergun
3 Star: Hot Lasergun
4 Star: Searing Lasergun
5 Star: Heat Wave

Niche

The Lasergun lines are your weapon of choice when getting closer isn't an option and there's so much going on you can't focus down a particular enemy. They have the most range out of any gun bullet in the game, and the charge attack practically has infinite range. With all this range naturally the damage will take a hit. I would suggest slightly less than Antigua Damage. The gun is incapable of flinching, but will allow you to hit targets you otherwise could not.