The .357 Magnum Revolver is a powerful handgun: more accurate and powerful than the Pistols, though with less common ammunition and considerably slower fire and reload times. It is featured in most of the Half-Life series' titles.
The Magnum is a double-action revolver which fires one round. Whilst it is very powerful, it has a long reload time and low rate of fire. It has near perfect accuracy, but rapidly firing shots will cause accuracy to significantly decrease because of the weapon's fair amount of recoil.
- In Half-Life, the Magnum can first be picked up near a dead security guard in the chapter Blast Pit, near the Tentacle roots under Silo D.
- In Blue Shift, the weapon can be found in the chapter Captive Freight next to a dead security guard outside of a car.
- In Half-Life 2, the weapon can first be found in the chapter Water Hazard, in a Civil Protection outpost on the Canals. Like most weapons, it can be acquired later; near a Citizen's corpse at the Petroleum Station along the Coast, for instance.
- In Episode Two, whilst in the Antlion caves in the Victory Mine, the Magnum can be found in one of the Antlion's nests, with ammunition available throughout the caves.
- In the multiplayer maps of Half-Life, the secondary fire button triggers a zoom which may be used for long-range sniper shots.
- Since it has no built-in scope in Half-Life 2, the HEV Suit zoom can be used to aim for long distance shots. It is advised to zoom into the target and have it in the center of the crosshair, then quickly release the zoom, then fire. Alternatively, the primary fire button may be held down while the zoom is being released to instantly fire a round and diminish jolting.
- Ammunition for this weapon is very rare in all of the games, so players should use this weapon only when its pinpoint accuracy and stopping power is required, such as against Alien Grunts or Overwatch Elite soldiers standing far away.
- Using this gun in the deathmatch modes can result in many easy kills at any range as long as the gun is aimed at the head.
- This is the most effective firearm against Hunters. The source code for Episode Two states that this is because players perceive the weapon as the strongest in the game.
 Behind the scenes
- As heard in the unused Half-Life sound file
get_44pistol.wavfor the HEV Suit and as seen on the cut ammo box model, the Half-Life Magnum was originally to be a .44 Magnum revolver.
- The Half-Life Deathmatch Magnum model features an attachment under the barrel that resembles a laser pointer but acts as a scope and emits a fake laser (as a small red dot in the center of the screen). While that scope is not present in Half-Life Deathmatch: Source, its function remains. This attachment was originally to appear in Half-Life's singleplayer mode as well.
- In the Half-Life 2 series, all six cartridges of the Magnum's cylinder are reloaded together, but there is no speedloader (the cartridges just float in mid-air as a circular group). The animation is instead more suited for the application of a moon clip. Overall, this is merely a design oversight.
- "Colt Python Elite" can be seen on the weapon's Source viewmodel. However, the worldmodel has the words "Colt Anaconda" on the side.
- During the Magnum's reload animation in Half-Life 2, the casings ejected by the gun will not appear on the ground. This has been fixed in Episode Two.
- In the Half-Life 2 series, on the weapon's viewmodel cartridges "Federal 357 Magnum" headstamps can be seen. Taking into consideration cartridges in ammo boxes, it can be concluded that Gordon uses Federal .357 Magnum JSP ammunition, although design of the .357 Magnum boxes themselves could be based on PMC ammunition boxes.
 Half-Life and expansions
 Half-Life 2
Citizen who committed suicide with a Magnum at the Petroleum Station, along the Coast.
 List of appearances
- Half-Life (First appearance)
- Half-Life: Blue Shift
- Half-Life 2
- Half-Life 2: Deathmatch (Non-canonical appearance)
- Half-Life 2: Lost Coast (Non-canonical appearance)
- Half-Life 2: Episode One
- Source Particle Benchmark (Game files only) (Non-canonical appearance)
- Half-Life 2: Episode Two