The .300 Blaser Magnum is a rifle cartridge developed by the German firearm manufacturer Blaser. Introduced in the early 2000s, it is designed for hunting medium to large-sized game. The .300 Blaser Magnum is known for its high velocity, flat trajectory, and good energy retention, making it suitable for long-range shooting. The cartridge typically features bullets weighing between 165 and 180 grains, achieving muzzle velocities around 3100 to 3200 feet per second, depending on the load.

It is based on the .404 Jeffery case, necked down to accept a .30 caliber (7.62mm) bullet, allowing it to offer performance comparable to other .300 magnum cartridges. The design allows for strong terminal performance and can be effective on game such as deer, elk, and even larger species like moose.

The .300 Blaser Magnum has gained popularity among European hunters and is appreciated for its accuracy and performance. It is also becoming more recognized in other parts of the world. The cartridge works best in bolt-action and single-shot rifles that can handle its larger size and pressure.