What do you use to repair that gun in fallout new Vegas?

Answer 1

Unfortunately since it's so unique (a pistol cut down from a rifle), there isn't a regular version to use for repairs. Your only options are to use a repair kit or pay certain individuals in the wasteland such as Freeside's Mike & Ralph's

Answer 2

• Anchorage!">You must have the DLC Operation Anchorage!

Then you must play till you see an American soldier get shot down and you will pick it upOut of simulation you get it by opening the armory door which you do by finishing operation anchorage and be prepared some of the outcasts will attack u when your in the armory

Answer 3

You can't.

There is only one Gauss Rifle in the game, no other weapon can be used to repair it.