Accelerated Charged Particle Repeater Gun
The Accelerated Charged Particle Repeater Gun. commonly known as the ACP repeater gun. was a medium-range blaster manufactured by Arakyd Industries. It was popular amongst criminals, most notably the Trandoshan mercenary group. These guns were not at all advanced and had built-in extinguishers in case of overheating.
They were capable of cutting through shields with ease, but relatively ineffective against battle droids and other armored surfaces. Also, after being fired repeatedly, the gun would overheat and start to go off target
Each particle ammunition cartridge consisted of forty small particle charges that were the source of energy for the accelerated particle shots
the gun fired. Upon activation, each particle charge had enough power to fuel one shot, after a particle charge had been fired, the empty shell of that charge was ejected out the top of the gun; this cycle continued until the entire ammo cartridge ran out, or when the holder took his or her finger off the trigger. The ammunition feeds in to the back from a top-back mounted magazine. It seems that the weapon also used some kind of tracer-ammunition, as the accelerated-charged-particles couldn’t be seen when fired. However, the LS-150 Heavy ACP Repeater fired bigger and more energized rounds which could be seen without additional tracer-ammunition.Source: starwars.wikia.com