The Gauss rifle, also called a coil gun, is a device used to propel a ferromagnetic projectile by accelerating them through a process of magnet induction. The Gauss rifle (and Gauss gun) are named after German mathematician Carl Friedrich Gauss, who formulated mathematical descriptions of the magnetic effect demonstrated by magnetic accelerators.
The scoped Gauss rifle is an advanced sniper rifle, that uses a series of eleven electromagnetic coils to energize and magnetize a pre-loaded standard projectile round at tremendous speed. In appearance, it is almost identical (apart from the addition of the buttstock), to the Gauss rifle acquired after finishing the Fallout 3add-on, Operation: Anchorage.
Like most other energy weapons in Fallout: New Vegas, this weapon is hard to maintain; identical Gauss rifles are rare in the Mojave, therefore making it more difficult to repair. Ammunition is also harder to come by than other weapons; this is coupled with its requirements of five microfusion cells per shot, as opposed to its Fallout 3 counterpart, which required only one. On the killing shot, the Gauss rifle's powerful beam causes a small distorted shockwave which will send enemies flying back.
The rifle has numerous advantages over its gun equivalent, the anti-materiel rifle. It has a lower Strength requirement of 5 compared to 8, does slightly more damage, has double the critical chance (a maximum of 76% compared to the 38% of the anti-materiel rifle), has more common ammunition, and weighs less. Finally, it has enough range to hit anything the player can see, whereas bullets may be unable to hit targets at the edge of the player's vision depending on the player's position and direction.
In Hardcore mode, if you carry more than 260 microfusion cells, or 52 shots, the Gauss rifle becomes heavier than the anti-materiel rifle. If you take the Heavyweight perk, it comes down to 60 cells, equivalent to 12 shots.
YCS/186 - a unique variant which does over 16% more damage and uses four microfusion cells per shot instead of five. It can only be obtained without the Wild Wastelandtrait, otherwise it will be replaced by an alien blaster.
When used in combination with the Meltdown perk, enemies killed with the rifle will frequently be launched incredibly high. This is due to the force that is normally applied to the target upon impact being compounded by the perk's explosive effect.
The AP requirement in V.A.T.S. for this weapon is actually higher, as reloading a weapon costs some AP as well and this weapon has to be reloaded in every shot, so the AP requirement is 10 AP higher in practice (as defined by the fActionPointsReload setting in the toolset).
The magnification level for the Gauss rifle's scope is 3.5x.
A single shot in Hardcore mode will use 0.5 pounds of ammunition, costing at a combined value of 15 caps per shot.
Because the Gauss rifle uses five microfusion cells per blast (which only accounts the fact that you fire once), it's only possible to get one empty microfusion cell from firing the rifle. This is also the same with all energy weapons that use more than one cell per shot.
Despite the gauss rifle fires magnetized rounds, no ammunition other than microfusion cells is ever consumed. The player never needs to insert more rounds into the rifle, making its supply of pre-loaded magnetized rounds a mystery.
When aimed straight down, the blast from the rifle will not knock the player down, nor will he/she take any damage like that of the Gauss rifle in Fallout 3. The shield indicating that the weapon's damage is being absorbed by the player's DT will appear, however.
pcxbox360ps3 The Pip-Boy's displayed damage per second (DPS) for the gun doesn't account for the need to reload every shot, unlike other single shot weapon such as the missile launcher. This is due to the game mechanics not taking into consideration the weapon use of more than one ammunition per shot. [verified]
pcps3xbox360 The Gauss rifle will rarely completely pass through an opponent when shot outside of V.A.T.S.. [verified]
pcps3xbox360 The Gauss rifle in Fallout: New Vegas is almost identical to the one found in Fallout 3, and thus suffers from similar bugs, including the one that affects its damage output when fired via V.A.T.S. When used in V.A.T.S., any hit will do exactly 95.244% of the maximum damage, regardless of enemy damage threshold, critical hits, or sneak attack critical. This means, that with an energy weaponsskill of 100, the Gauss rifle shot will do 114.29 points of damage with every V.A.T.S. shot. This is still lower than free aiming, and no bonuses are applied to head shots. The damage bug is related to the Gauss rifle's "explosive" visual effect, which affects its V.A.T.S. damage calculations. Removing the effect via user-created mods is currently the only known solution to the issue. Notably, the displacer glove, which applies a similar visual effect on impact, is not affected by this bug. [verified]
ps3xbox360 When scoped in, the rifle shows a high-contrast color computer interface as shown when activating a terminal, meaning your view will be completely impeded. [verified]
ps3xbox360 When standing still and aiming straight down, then firing the weapon, the player will sometimes go into third-person, and the weapon will then fly out of the player's hands. While in third-person, the weapon will now fire directly from where it lies on the ground, or sometimes, float in the air. If entering first-person, the weapon acts like normal. The bug can be fixed by unequipping the weapon completely and re-equipping it again. This is also possible for its unique variant, the YCS/186. Since both weapons have a small area-of-blast damage, this will also damage the player for about one-tenth of their health. [verified]
↑Emil Pagliarulo in the Bethesda Game Studios forum  - "The gun energizes and magnetizes a standard projectile round; those are already pre-loaded into the weapon, and are in that giant clip attached to the side of the weapon... We did it this way because we knew we wanted to have an energy weapon equivalent of the sniper rifle"