The Browning Hi-Power appears as "9mm Pistol". Can be modified with an extended magazine and a scope. A unique version called "Maria", decorated with a Virgin Mary furniture, is available.
Colt Single Action Army
Appears as ".357 Revolver". It is chambered in .357 Magnum (so it could be the almost identical externally Ruger Blackhawk).
Colt Model 733
The Colt Model 733 appears as "Military Assault Rifle" with what looks like a 20 round magazine.
AR-15
An AR-15 is seen being wielded by NCR soldiers, called "Service Rifle" in-game. It has a wooden stock similar to the AR-10 however it is patterned after the M-16A1 Vietnam era triangular hand guard. It is chambered for 5.56x45mm NATO and is semi-auto. The upper receiver has forward assist and a case deflector.
M1 Garand
M1 Garand appears in Fallout: New Vegas Called the Semi-Automatic Rifle.
Over and Under Shotgun
Called the "Sturdy Caravan Shotgun" in game. It can be found in a pre-order bonus picture
M79 Grenade Launcher
Seen in a pre-order bonus picture. It is called the "Grenade Launcher", with a unique version called "Mercenary 40mm Grenade Rifle" available as a pre-order bonus.
Winchester 1886
The Winchester 1886 appears as the Cowboy Repeater, it takes 357. Magnum ammunition and it can take down light armoured enemies from a distance
Winchester 1887
It differs from the real life model in that it ejects shells from the bottom akin to Ithaca 37 and it's fed with 20-gauge shells.
M60 machine gun
It looks like there is going to appear a modified M60 with wooden lower hanguard as seen in Fallout 2. It seems it has some kind of magazine instead if side-inserted belt.
M3 "Grease Gun"
An M3 Grease Gun appears incorrectly chambered in 9mm, called the "9mm SMG" in-game.
American-180
A .22-caliber SMG with a pan magazine and integral suppressor.
LAPD 2019 'Blaster'
The pistol from Blade Runner makes a return to the Fallout series. Called "That Gun" in-game, it uses 5.56mm cartridges.