The Shock Blaster is one of the two weapons you get for free at the start of the game. It fires a blast of reddish energy which functions like a shotgun - this weapon does more damage at close range.
V1: Power is 40. Maximum ammo is 30.
V2: Power increases to 50. Maximum ammo increases to 35. The weapon can now perform a more powerful charge attack (hold down fire).
V3: Power increases to 60. Maximum ammo increases to 40. The weapon can now lock-on (hold 
+
).
V4: Power increases to 80. Maximum ammo increases to 45. The weapon now shocks any enemies nearby the target (Shock Mod).
V5: Weapon becomes Shock Cannon. Power increases to 100. Maximum ammo increases to 50. The weapon now has the Beam of Death function for a charge attack, which consumes 10 ammo.
Shock Cannon
This is an awesome upgrade to an already useful weapon. The blasts become blue (the same colour as a charged up Shock Blaster shot). The Beam of Death becomes the the charge attack, and it's extremely powerful - it can kill most enemies in one hit and although it doesn't last for very long you can quickly spin on the spot and hit a load of enemies. The ammo consumption of this however means you can't use it very often.
Uses
This weapon is great; it's free, effective and user-friendly. The Shock Cannon's Beam of Death feature makes it one of the best weapons available, especially near the beginning of the game. Against bigger, badder enemies this weapon isn't very useful, but against large groups of small enemies this will serve you well.
Mega Shock Cannon
The Mega upgrade for the Shock Cannon costs 420,000 bolts.
V6: Power increases to 1,100.
V7: Weapon becomes Giga Shock Cannon. Power increases to 1,400. Maximum ammo increases to 55.
V8: Weapon becomes Omega Shock Cannon. Power increases to 2,100. Maximum ammo increases to 60.