Dino D-Day was originally a Half-Life 2 mod that was later released as a stand alone Multiplayer FPS game on Steam. The game is set in World War II with a twist: The Nazi's have somehow created Dinosaurs that they use to fight the war. Gameplay is similar to Team Fortress 2.
The M1911A1, called the Colt .45 in-game, is the sidearm for Hardgrave and Cpl. Joe Spencer.
Nagant M1895
Called the Nagant Revolver, it is the sidearm of Ilona Vike.
Walther P38
The Walther P38 is the sidearm for Camille Brun, the Allied Medic. In-game the name 'Walther' is dropped and it is simply referred to as the 'P38'. Oddly, despite being a weapon heavily used by the Germans during World War II, this weapon is used by an Allied character.
Luger P08
Olt. Karl Hissman and HptFw. Wolfgang von Graff both carry a Luger P08 (Simply called Luger in-game) as their sidearm.
Rifles
M1 Garand
Capt. Jack Hardgrave can carry an M1 Garand as his primary weapon. As with most video game incarnations of this weapon, you can only reload when the weapon's current clip runs dry.
M1 Carbine
Hardgrave can also carry a M1 Carbine as the primary weapon if the player chooses so. The weapon carries more ammo than the Garand and can reload mid-magazine, but deals less damage to enemy players.
Mosin Nagant M91/30
The Mosin Nagant appears as the Mosin-Nagant, and has an attached sniper scope. It is the primary weapon of the Allied sniper Ilona Vike.
Karabiner 98k
The Karabiner 98k appears as the Mauser 98k. It is the primary weapon of both Hptm. Kurt Streicher and Hissman. Hissman, being the Axis sniper class, has a scoped variant. Additionally, unlike Streicher, Hissman loads his weapon one bullet at a time, probably due to the scope. Streicher uses a 5-shot stripper clip.
Sturmgewehr 44
The Sturmgewehr 44 appears as the MP-44. It is the primary weapon for von Graff.
SMGs/Machine Guns
M1A1 Thompson
The M1A1 Thompson appears as the Thompson SMG. It is one of two primary weapons for Spencer.
M3/M3A1 Grease Gun
The Grease Gun is the other selectable primary weapon for Spencer. It does more damage, but has a slower rate of fire and less accuracy.
Sten Mk II
The Sten Mk II appears as the Sten Gun and is the primary weapon of Camille Brun.
BAR
A BAR without a bipod is the primary weapon for Joseph Frank.
MP38
The MP38 appears as the MP-40, and is the secondary weapon for Streicher.
Browning M1919A4
The Browning M1919A4 appears as the .30 Cal MG, and is the weapon attached to the back of the cyber-Protoceratops, Trigger. The weapon cannot be reloaded, but can overheat, and if it fully overheats, the weapon must cool down completely before being used again. Once ammo is dry, Trigger must find ammo on the ground or resupply back at the base.
MG34
The MG34 is the weapon that is mounted on the back of the Axis Stygimoloch. It acts like Trigger's .30 Cal MG.
MG42
MG42s appear as mounted weapons near Allied spawn points on some maps. It has unlimited ammo but can overheat like the Browning and MG34.
Shotguns
Winchester Model 1912 Trench Gun
The Winchester Model 1912 "Trench Gun" appears as the Trench Gun. It has the slowest reload of all the weapons players can use. It is the primary weapon for Blithe-Crossley.
Flechette Gun
Frank's sidearm is a weapon called the Flechette Gun. It is a single-shot handgun that fires shotgun shells and appears to be a heavily modified double-barreled shotgun of sorts. The weapon has zip ties around it, which is anachronistic as they weren't invented until 1958 and the game takes place around 1944.
Rocket Launchers/Explosives
PIAT
One of two secondary weapons for Blithe-Crossley, the PIAT is the game's rocket launcher.
Mk 2 Hand Grenade
The Mk 2 hand grenade appears as the Mk 2 Frag Grenade, and is used by both Hardgrave and Frank as explosives.
Sticky Bomb
Called the Sticky Bomb, this is Spencer's explosive.
Model 24 Stielhandgranate
The Model 24 Stielhandgranate, with a fragmentation sleeve, appears as the Stick Grenade, and is used by both Hissman and Streicher. Von Graff uses a healing pack in the grenade's place. Similarly, Brun also does not carry an explosive, a common trait between the medics. Model 24s are also used by the Axis Compsognathus (Compy) class, who wears one on their back. Compies act as suicide bombers.
Smoke Grenade
Blithe-Crossley also carries a Smoke Grenade.
Other
M2 Flamethrower
The M2 Flamethrower appears as the Flamethrower, and is the second option players can choose to use for Blithe-Crossley's secondary weapon.
20mm Gun
The weapon emplaced on the back of the Axis Desmatosuchus.
Jack Rabbit
Vike can dispense Jack Rabbits to distract Velociraptors and Microraptors. She can kill them while they're eating and as the other player looks on in shock and anger as his dino is gunned down in front of him while eating the rabbit.
Fists
All allied characters minus Trigger can use their Fists as a backup weapon.
Knife
German human classes use knives as a backup weapon.