These direct-fire weapons do not include splash-damage effects. They may have other damaging effects such as the flamethrower's fire-based damage-over-time.
Rock-It Launcher - DPS: Variable - The Rock-It Launcher is an outlandish and possibly effective weapon which can fire all sorts of trash at your enemies. To use it, you'll need to load it with ammo - virtually any piece of junk - and that ammo will dictate both how much damage you can do and the way the weapon fires. Generally speaking, common, cheap, bullet-shaped items are the best, as they fly straight and will make hitting your target much easier. They're also lighter, which makes it possible to actually carry a large volume of ammo.
The Rock-It Launcher can only be obtained by building it. Once you've obtained three of the Rock-It Laucher schematics, you'll be able to build Rock-It Launchers, which always do maximum damage and are easier to repair.
Minigun - DPS: 50 - The Minigun is what you would expect. It spits out a hail of bullets at your enemies, causing a very high amount of damage in a short period of time. In the early-mid game, this is easily one of the most effective weapons you can have for medium range combat, but the gun does have its drawbacks. The largest of these is that it eats through ammo very quickly. The gun also has a warm-up time, which means you'll have to wait a few seconds before it will begin to fire. The Minigun is good for use in early-game situations where you find yourself attacked by enemies which your puny Laser Pistol can't damage, but by level 10 you'll have access to far better weapons.
Flamer - DPS: 64 - The Flamer is one nasty piece of work. Although Fallout 3 disappointingly does not feature enemies which run screaming in agony once set ablaze, you'll still find that the Flamer is capable of making short work of almost any foe. Up until your early teens, this gun will be your doomsday weapon of choice whenever you find yourself in close-combat. Just like the Minigun, the ammo for the Flamer runs out fast. Be careful to use it only when you have to.
For maximum firepower, combine the Flamer with the Pyromaniac perk. With this perk, the Flamer is one of the most powerful weapons in the game.
Gatling Laser - DPS: 80 - The Gatling Laser to be honest, isn't going to win any points of orginality. It operates very similar to the Minigun, except that it doesn't have a warm-up time and it does more damage. It also appears to be more accurate. These incremental improvements aren't exciting, but they do make the gun a good choice through the game. Ammo shortages will remain a problem, but - unlike when you were limited to the Minigun - you should now have enough cash to buy out the ammo stock of every gun store in the Wasteland.