Fallout Weapons

The weapons in the first Fallout game were mostly generic, they had names that sounded plausible but were at least inaccurate. The Colt 6520 is not a pistol but a carbine, there is no HK MP-9 (it was probably originally supposed to be an Uzi, at least that's what the graphics are named), the Colt Rangemaster is a scope, not a rifle, and the only thing that ever bore the number DKS-501 is a German package machine.

The weapons introduced in Fallout 2 mostly were more or less exact representations of actual weapons. These are all outside links.

Desert Eagle

One of the few guns in the first Fallout game that didn't exist in the fifties.

FN FAL

A good weapon, but not exactly an assault rifle, this article says.

Gauss Rifle

It exists as a science toy, but not as a weapon.

HK CAWS

Seems this weapon never really went into series. It dates from the eighties.

HK G11

Developed in the late 60s, it is actually a bit too young for the Fallout world. But its representation in the game is fairly exact. BTW the HK G11 is more an assault rifle than a submachine gun.

HK P90c

The actual weapon that most likely served as a model for this is the Belgian FN P90. It uses a special 5.7mm ammo and has a far larger magazine (50 rounds).

Mauser

A couple of blunders here: The Mauser C-96 had a 10-round, occasionally 6 or 20, but definitely never a 7-round magazine. It was rather heavy. It originally used 7.63mm ammo, which is indeed very rare, whereas the 9mm army variation used standard 9x19 Luger/Parabellum ammo. Mausers were first used in the Boer war and developed up to the early 30s.

M3 Grease Gun

A pity the designers made the .45 ammo so rare. This gun dates from 1942.

Pancor Jackhammer

Like the HK CAWS, it dates from the eighties.

Red Ryder BB Gun

Yep, that's a real one too. It's from 1940. Red Ryder was a popular newspaper comic strip 1938-64 that was the basis of several movies and TV series.

Thompson (Tommy) Gun

XL70E3

An experimental weapon from the late 60s/early 70s, this, too, is a bit young for the Fallout world.

The .223 pistol may have been inspired by Deckard's blaster from the movie Blade Runner. Indeed the graphic bears the name dekker (a common misspelling of Deckard), and the blaster prop was made from a Steyr Mannlicher .222 Model SL rifle. There are several replicas of the prop, by Phil Steinschneider (with extensive documentation) or EDCstudios, for example.

Interesting enough, the Bozar does not seem to exist outside the Fallout games. Its graphic is probably taken from a heavy sniper gun.