Rifles are solid shell or energy-based firearms that are either hand-held or arm-mounted by an AC or MT unit. Rifles are slower than Machine Guns, have less ammo, and also tend to be heavier (with some exceptions). However, they make up for their slower speed and heavier weight with more firepower, accuracy and impact force. There are several types of rifles:
Basic solid-shell rifles with adverage performance specs. They tend to be well-rounded, but they often lack some of the higher performance specifications of other Rifle types. Starter AC's often come equipped with one of these rifles.
Rifles that use energy rounds instead of solid shell ammunition. They are slightly more powerful than most other Rifle types, but they draw power from an ACs energy supply, making energy efficiency a must.
A hybrid of Rifles and Machine Guns, the Assault Rifle class has respectable power and a higher rate of fire than Standard Rifles (although they are still slower than Machine Guns). However, the size of the rounds they use limits their magazine capacity; this, coupled with their high rate of fire, tends to cause ammunition shortages in battle.
Sniper Rifles are very slow and heavy, but their range is nearly unmatched and they pack quite a punch. Because of their slow rate of fire and slow aiming, they are not suitable for close-range fighting. Sniper Rifles come in Solid-Shell and Energy Based versions.
The little brother of shoulder-mounted Grenade Launchers. Sometimes referred to as "hand-held Grenade Launchers," Grenade Rifles are easily one of the most powerful Rifle types. They fire high-explosive rounds with stun capability and crushing attack power. They are also heavy, have a slow rate of fire, have a limited magazine capacity, and are difficult to use - especially in close-range combat where the user could become a victim of his own Grenade Rifle's splash damage. The projectiles they fire are also relatively slow in speed, making it quite possible for a skilled pilot to avoid them.
Plasma Rifles are energy-based weapons that fire bolts of superheated, highly concentrated plasma suspended in a magnetic field. Their attack power is fearsome, and they can also cause great amounts of thermal stress when they hit a target; a single hit could rocket an AC's core temperature well over 500 degrees Celsius, which could cause a number of dangerous situations (AP drainage, overstressed generator, etc.) if the AC in question did not have adaquate cooling systems. However, Plasma Rifles are also slow, heavy, and drain great amounts of energy when fired (compared to Laser Rifles).
Much like a cross between Railguns and Standard Rifles, Linear Rifles are shell-based weapons that fire high-mass depleted uranium slugs at high speeds. Although their firing rate is slightly slower than Standard Rifles, and they carry less ammunition (most Standard Rifles carry about 120-150 rounds; Linear Rifles carry 50-80), they more than make up for it with above average power and stun capability. Their largest drawbacks could be their weight and energy consumption when equipped.
(Note: Despite seeming to be a "railgun" that uses electromagnetic coils to launch projectiles, Linear Rifles do not consume the AC's generator energy when fired. Possibly they have their own, separate generator).