The particle rifle was a type of standard-issue carbine directed energy particle weapon used by United Earth's MACO personnel in the 22nd century. They are very similar in technology to the class-3 pulse rifles Starfleet Security uses. However these are designed to be able to operate in harsher conditions then their Starfleet counterparts. These weapons had a range of about 70 meters.
The particle rifle fired discharges of blue bolts of concentrated energy. The weapon could also be set to fire orange-red particle beams similar to those fired by a plasma rifle or a phase pistol. The particle rifle was capable of multiple power settings, ranging from stun, to kill, to a high-power shot capable of blasting through a Human torso. Power levels could be changed by manipulating either of a pair of circular dials mounted on either side of the weapon. The weapon featured a tubular stock, vertical foregrip, and a multifunction scope that could be retracted into the body of the weapon.
While extremely powerful when set to kill, its stun setting appeared to be somewhat ineffective against species that were more physically resilient, such as enraged Vulcans, Xindi-Reptilians and the Augments. At their highest setting, MACO particle rifles were extremely powerful, capable of penetrating a humanoid target. In 2154, Captain Archer used a MACO particle rifle to kill the Augment Malik in this manner, using the rifle to literally bore a hole through Malik's torso.
In a MACO weapons training simulation, a skilled user could score as many as 14 hits in 10 seconds with a particle rifle. In 2153, Corporal Amanda Cole held such a record at level 4 of the simulator. Though she insisted, she was just having a lucky day.
Particle rifles were in use as late as 2161, when a team of MACOs utilized the weapons during a mission to rescue Talla, the daughter of Shran and Jhamel, from a group of alien kidnappers on Rigel X. The particle rifle was still used by MACOs in the 24th century.