Sniper Rifle

The G3 is a Hunting Rifle in Left 4 Dead 2.

Differences
Compared to the Left 4 Dead Hunting Rifle, the G3 has a larger magazine (30 rounds) and has a tighter crosshair when moving or getting hit by enemies.

Tactics

 * 1) The G3 is simultaneously the most and least accurate weapon in Left 4 Dead. While moving (unless you are using the scope) or taking damage, each shot is almost guaranteed to miss. Pistols are generally more effective while on the move or being hit. Using the rifle's scope while moving is another useful option, and allows the player to quickly cover the team without stopping. Note that activating the scope tightens the crosshairs faster than standing still.
 * 2) Every hit is a guaranteed kill on Common Infected. So, for the hunting rifle, headshots are wasted on them. Aiming at the chest affords the best chance of striking many Infected in a line.
 * 3) Although the hunting rifle boasts considerable stopping power against Common Infected, its power is mitigated against Special Infected. Aim for the head to compensate.
 * 4) Fire slowly. Although the hunting rifle has a good rate of fire, firing quickly is only effective on the Tank or Witch, both of which require multiple shots to kill. Conversely, more than one shot fired into a line of Common Infected is wasted.
 * 5) Reload strategically. Although this is generally true of every weapon, firing fifteen quality shots with the hunting rifle during a minor horde event is fairly rare. Be aware that the hunting rifle takes significantly longer to reload than the assault rifle, and cannot be canceled like the auto shotgun, so keep your magazine full enough to protect team members from Special Infected.
 * 6) The hunting rifle is a one hit kill on the horde, no matter how much HP they have (the rifle does about 75 damage per shot, the horde has 90 health on expert, and the hunting rifle still kills them in one hit). The rifle does kill any number of zombies in the horde by penetrating, as long as they are appropriately lined up.
 * 7) Be incredibly careful of friendly fire. This applies the most on expert difficulty, as one shot will leave a Survivor with very low health, and an easy target for any Infected.
 * 8) In hallways, tunnels, and other areas where the horde is funneled towards you, the hunting rifle is incredibly potent. Since it kills infected in one shot and the shots can pierce through a large number of Infected, it is possible to clear out a large horde in just a few shots.
 * 9) It is possible to kill a Witch with a single hunting rifle and without help. Head shotting her head, and shoot her body with another 14, this is helpful on expert too. If you fear you will miss a bullet, use your pistols, as maybe hunting rifles can do more damage than pistols, they are your only last hope to survive you if you miss one bullet from your hunting rifle.