Pistol

Summary
The pistol is most likely the best gun in Halo 1, for all situations. In Halo 2, it was replaced by the considerably weaker Magnum.

General Info
The pistol is sometimes called the greatest weapon. That's probably not the complete truth. Perhaps it's just the best multipurpose weapon. It's got long range, short range, cheap ammo, and best of all, accurate. Although it's accurate, it isn't a one-shot kill in most situations, and it's not the Sniper Rifle. What generally works is if you shoot a lot of shots at a time at the enemy. It takes shield off quickly, and same for health. It is the most well-rounded weapon.

Long Range
Just zoom and shoot. If you've got an easy, standing still target, like someone about to snipe, try to shoot them in the head. After that, it's likely that they will notice you. Then just shoot a lot. It's also just about as fast as the sniper rifle, so don't aim right at them, unless they are standing still. If you can aim right at them and hit them, it's short range.

Short Range
Just unload a lot of rounds into your enemy. Aim for the head, shoot a lot. Move towards the enemy unless they have a weapon that will hurt you if you get closer (like the Shotgun or the Flamethrower).

Warthogs
This is the best weapon against a Warthog, other than an explosive. It isn't like the other weapons, the Warthog doesn't give it protection from pistol shots. However, the Assault Rifle is good against these vehicles too.

Any other seat for a Warthog is very good for the pistol, as good as someone on foot. The thing, though, is that the gunner seat is better for the pistol than a lot of other weapons, at least for long range. Just aim for the head. It is better for long range, because it's harder for them to hit you, so you can snipe (with the pistol, of course).

Ghosts
Try to get on the sides, and once again, aim for the head.

Tanks
This isn't at all good for handling tanks. Not much to say.

Banshees
This is not a very good weapon against Banshees either. It is a good weapon, but if I could choose a weapon to kill a shee, I wouldn't choose a pistol.

General Equipment Guide
Newbies hate it, but pros swear by it and guess who wins in a fight? The standard issue human sidearm may seem underpowered on a purely visual and auditory basis, but like a real pistol, it's every bit as vital as the body part you aim it at. In this case, we recommend the head. Three headshots on a fully shielded human will drop him or her like a sack of burning crap. Why? Because - and not a lot of people know this - the pistol does lethal one-shot headkills. The reason fools don't drop more readily is that unlike the sniper rifle, pistol shots are blocked slightly by shields - but once the shield is gone - a single pop to the head should suffice. Thanks in no small part to its 12.7 mm, semi-armor piercing, high-explosive rounds; it will even come in handy as you take on vehicles by foot. INSIDER TIP: Although accurate pistol shots will bring down foes very quickly, the effect of two or more teammates using pistols on the same target is devastating. If you have a buddy who'll cooperate, you can take out vehicles and pedestrians almost instantly and from great range. You could also combo with a Plasma Pistol - one overcharge shot followed immediately by one pistol shot to the head is lethal to any shielded foe.

Multiplayer Guide
The pistol is arguably the best overall weapon in the game. If you find a pistol lying around, pick it up and use it! Good in almost all situations, long range or short. Once you get those shields off your opponent he's as good as dead. Go for head shots! Practice keeping the pistol sight at opponent head level during game play, and head shots will become more natural. Remember, the pistol has a zoom, but it takes time! Try to keep a longer range on other players when using the pistol. Full auto is not as accurate as single fire, so "vid" the pistol: squeeze the trigger for each shot. You'll be much more accurate that way. The only downside of the pistol is the relatively slow melee attack, but don't discard an empty pistol too quickly; ammo from dead players is often abundant.

Combos
The pistol by itself is a wonderful gun, but combos can make it better. These combos are listed in order of use.

Pistol & Shotgun If you need to do long range, go ahead. It's also good if you have to do close range, because of the Shotgun.

Plasma Pistol & Pistol If you charge up a plasma pistol shot and hit an enemy with it, the pistol can take care of them quickly.

Pistol & Assault Rifle The pistol can take off shields quickly, and then the AR can finish the rest of the health.

Pistol & Sniper Rifle It's everything and long range. This is not a good combo for small levels with a lot of people.

Technical Data
Rate of Fire : Average, semi-automatic (3.5 rounds per second) Damage per Hit: High Range        : Medium to long Accuracy     : High Calibre      : 12.7 mm semi-armor-piercing, high-explosive rounds. Magazine Size : 12 rounds Maximum Ammo : 132 rounds (including a fully loaded magazine)

PC Game Manual
"This pistol is a recoil-operated, magazine-fed handgun. It is issued with a smart-linked scope capable of a 2x magnification .  It fires 12.7 mm semi-armor-piercing, high-explosive rounds.  It can shot either semiautomatic or automatic fire."