Sniper

Sniper is a perk in Fallout, Fallout 2, Fallout 3 and Fallout Tactics: Brotherhood of Steel.

Fallout, Fallout 2 and Fallout Tactics
You have mastered the firearm as a source of pain. With this Perk, any successful hit in combat with a ranged weapon will be upgraded to a critical hit if you also make a Luck roll. It adds another luck roll of (10*Luck). 10 LK means every hit is automatically a critical hit.

Fallout 3
With the Sniper perk, your chance to hit an opponent’s head in V.A.T.S. is increased by 25%. As with most perks that increase your chance to hit in V.A.T.S., this bonus is multiplicative, not additive.

Bugs
As of version 1.1.035, it has been proven on the PC that this perk is nonfunctional, similarly to Commando, Gunslinger, and Wired Reflexes. It has not been fixed in 1.4.06, and it is not known if the X360 and PS3 versions are affected due to the lack of any controllable means to test.