This .357 Magnum gives Gordon all the stopping power a man could want. You can acquire the Colt Python relatively early in both Half-Life games, providing some much needed firepower. If you’re able to land a shot on target, the Colt Python can usually bury an enemy in one shot. Careful with the recoil though; this thing kicks like a mule.
The only downside to the Colt Python is the rarity of its ammo, which is as scarce as can be. As such, you should really only use this magnum when facing down an exceptionally tough boss. The Colt Python has saved my skin more than once when the going got tough, so I had to include it on this list.