For boys and girls who like thermal particle destruction.

The Particle Projector Cannon is an energy weapon in the Mechwarrior universe that fires a concentrated beam of protons that cause damage through both thermal and kinetic energy. Due to the nature of the weapon, it rivals even the autocannon in terms of damage, easily melting through high grade armor, overloading systems or destroying targeting sensors before ejecting out the other side. It is feared on the battlefield for its sheer destructive power, and is infamous for turning tides of battles with a few well-aimed shots.

Now, why am I telling you this? Because on the Mechwarrior Online blog has a fun bit of fluff text that's worth a read if you're into high-velocity proton shots (and I just know you are).