The standard UNSC sidearm. Recoil-operated magazine fed handgun. 12 rounds per clip, and lacks the scope that it was equipped with in Halo: Combat Evolved. A shot in the forhead assures a kill, unless the opponent is shielded. It can be dual-wielded and exeptionally deadly if done so.
M/7 SMG
Dubbed the "Bullet Hose" by those who use it, the M/7 is the UNSC SMG. While a few shots do little damage, the full-automatic fire that it sprays is deadly, especially when dual-wielded. Bullets have no cases, so cleanup is left to those who move bodies.
BR55 "Battle Rifle"
Replaces the MA5B Assault Rifle from Halo: Combat Evolved, the BR55 is now equiped with a X2 scope and fires in 3-Round bursts. Extremely effective when used by a well-trained soldier, and good for blasting just about anything that moves.
S2 AM Sniper Rifle
The S2 AM is arguably the most deadly weapon in the UNSC roster. Featuring a X5 and X10 zoom, the .50 Caliber bullet fired is able to penatrate almost anything. A good marksman may be able to take out more then one target, and headshots are devestating on everything execpt Hunters.
M19 SSM MAV/VA Rocket Launcher
Best used as an anti-vehicle weapon, the M19 is also a very effective anti-troop weapon. Has two 102mm shells inside, which can home on vehicles. Also has a X2 zoom, to blow the living hell out of those far-away targets as well.
M90 Shotgun
If your looking for the most-effective close-range weapon, look no further. The M90 can take down nearly any shield with one blast, if close enough, and is exeptionally effective against The Flood.
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The standard UNSC sidearm. Recoil-operated magazine fed handgun. 12 rounds per clip, and lacks the scope that it was equipped with in Halo: Combat Evolved. A shot in the forhead assures a kill, unless the opponent is shielded. It can be dual-wielded and exeptionally deadly if done so. 
Dubbed the "Bullet Hose" by those who use it, the M/7 is the UNSC SMG. While a few shots do little damage, the full-automatic fire that it sprays is deadly, especially when dual-wielded. Bullets have no cases, so cleanup is left to those who move bodies. 
The S2 AM is arguably the most deadly weapon in the UNSC roster. Featuring a X5 and X10 zoom, the .50 Caliber bullet fired is able to penatrate almost anything. A good marksman may be able to take out more then one target, and headshots are devestating on everything execpt Hunters.
Best used as an anti-vehicle weapon, the M19 is also a very effective anti-troop weapon. Has two 102mm shells inside, which can home on vehicles. Also has a X2 zoom, to blow the living hell out of those far-away targets as well. 
If your looking for the most-effective close-range weapon, look no further. The M90 can take down nearly any shield with one blast, if close enough, and is exeptionally effective against The Flood.