The Concussion Gun is a weapon manufactured by Gadgetron in Size Matters. It fires a shotgun-like blast of devastating titanium pellets that deal more damage the closer the enemy is. It is the weapon of choice for the Galactic Ranger's riot squad.
The Concussion Gun can be purchased immediately on planet Pokitaru for 10,000 bolts. With use, it can be upgraded to the Concussion Cannon, a weapon that fires so much shrapnel that it is classified as a mobile artillery weapon on Xyxx VII. In challenge mode, the Titan Concussion Cannon can be purchased.
The Concussion Gun is a blue shotgun with a very wide barrel, with purple grips. The Concussion Cannon is a mostly blue weapon with purple highlights, which is longer and held by a grip on its back rather than a trigger beneath it. The available mods are the Lock-On Mod, the Split Barrel Mod, and the Charge Up Mod. The Split Barrel Mod (wrongly called the 'Split Barrel Mod') installs semi-legal expander modifications, increasing the width of the weapon's blast. The Charge Up Mod adds an extra chamber to the Concussion Gun, allowing it to store multiple shells to be unleashed in a huge blast.
The Concussion Gun is a shotgun which fires a blast over a large area, and can hit multiple enemies at once. Its damage is spread out over the shrapnel in each shot, meaning that to deal full damage to an enemy you need to hit them point-blank, or fire at groups. Though it can clear mobs of enemies early on, it is quickly outclassed by weapons later, becoming obsolete. The Concussion Cannon upgrade is a flat upgrade to the radius, range, and damage of the Concussion Gun, but nonetheless does not compete with later weapons.
The weapon has three mods available for it: the Split Barrel Mod for 15,000 bolts, the Lock-On Mod for 5,000 bolts, and the Charge Up Mod for 50,000 bolts. The Lock-On Mod will make it easier to hit very mobile enemies, whereas the Split Barrel Mod increases the weapon's blast range. Since the damage is split over the shrapnel, this means you spread out the damage even more, but can also hit more enemies at once. The Charge Up Mod, while the most expensive mod at 50,000 bolts, is also the most useful, as it allows the player to charge up shots by holding the fire button before releasing. A full charge drastically increases the total damage dealt, at the cost of needing to charge it up. This directly addresses the weapon's biggest shortcoming in its weak damage against single threats, though as it is an expensive mod, the player may choose to instead purchase another more powerful weapon first and buy the mod in challenge mode.