M7 Caseless Submachine Gun

Technical Data for SubMachine Gun
Official Designation   : M7/Caseless Sub Machine Gun "SMG" Projectile Type        : 5MM Dual-Wield             : Yes Damage                 : Low Range                  : Close Accuracy               : Low Rate Of Fire           : High Autofire Capability    : Continuous Fire Magazine Capacity      : 60 Bullets Ammunition (Additional) : 180 (3 Magazines) Reload Speed           : Slow Melee Attack           : Average Scope                  : No

Advantages
The SMG's strength is its high rate of fire. While individual shots are not enormously damaging, its full automatic mode of fire has led to it being dubbed the "bullet hose" by users in the UNSC. When dual-wielded, it allows the Master Chief to drown targets in a veritable torrent of projectiles.

The SMG has a number of shortcomings. Its accuracy is strictly limited unless used at close range. Furthermore, full automatic fire leads to enormous recoil, forcing the SMG's muzzle steadily upward. You will need to compensate for this effect by constantly adjusting your aim. Finally, its phenomenal capacity for filling the air with lead means that its magazine can be depleted in what will seem like a heartbeat. If there's no cover available to hide behind while reloading in your current area, you may be better served by another weapon.

Multiplayer Tactics
The SMG is the most commonly used and found weapon early in the game. Most games start off with someone wielding this weapon. Therefore, its the easiest weapon to find among the dead.

SMG + Plasma Rifle
SMG + Plasma Rifle is easily the best combination. Some argue that the SMG and Plasma Pistol are, but this combination is the easiest to fight off many opponents in one setting without having to recharge the Plasma Pistol. It also gives you the flexibility of using two weapons at once while simultaneously destroying the opponents shield and health. Remember to reload the SMG and make sure the Plasma Rifle does not Overheat.

SMG + Plasma Pistol aka Newb combo
Second best. Best at dealing with singular opponents. Be careful of the lapse between the Plasma Pistol recharge and the reload of the SMG. It is difficult to kill someone, and be able to fight someone right after. This is very easy to appear in small maps such as Lockout and Beaver Creek. Also be wary of the fact that the Plasma Pistol will eventually run out, sometimes quickly if you've been though opponent after opponent.

SMG + SMG
Probably the easiest combination to hang onto until you find a Plasma Rifle when you just respawn or the game begins. This combination is the most predominant in the level Foundation, where there are no Plasma Rifles and SMG are easy to find among lots of dead bodies and all over. This combination, however, is difficult to use in other places because of the problems of draining enemy shields. If you have Dual SMGs against SMG + Plasma Rifle, head on, you-will-lose. Also be aware that the Recoil effect of the SMG is doubled in this instance. A smart player dual-wielding two SMGs will pump the trigger (pressing it repeatedly) instead of holding down on both triggers to maintain a trade-off between accuracy and rate of fire.

SMG + Needler
Half-Decent combination. Not very useful. Easy to pick up in Burial Mounds (Level) and Beaver Creek (Level) where the Needler is close. The most important, and sad attribute to the Needler is a losing advantage. I've found (it could be my needler skills) that if this is your only solution, you've become Black in a chess game. You can only kill the person that has just stepped over you when they're pumped full of needler ammo, or die quickly, only denting their shields. The latter usually happens with a more experienced, strafing opponent.

SMG + Magnum
This can be the worst combination, or even better than dual SMGs, depending on your skill. If you are able to deplete enemy shields, and aim right at the head with the magnum. This can make or break a starting game, usually on Beaver Creek, where the Magnum is in easy reach from the Spawn Points.