In recent years, there has been a 300 magnum revolution. That revolution was kick-started by calibers such as 300 Norma and 300 PRC. These powerful cartridges combined modern case design with long, sleek, high BC bullets to create rounds capable of hitting targets at extreme distances. But what about the granddaddy of them all—the 300 Winchester Magnum?
The question was: Is the 300 Win Mag still relevant? The cartridge debuted in 1963, just in time to be chambered in the beloved rifleman's rifle—the Winchester Model 70—before engineering changes the following year. The cartridge made headlines as a hunting round capable of taking down North America's largest game. Undoubtedly, you'd be hard-pressed to find a magnum caliber that had taken more game. It was also the cartridge used by famed Marine Corps sniper Carlos Hathcock, as he rewrote the record books at Camp Perry and in Vietnam. But in 2025, was this historic belted magnum still relevant in an age of ballistics revolution? That's what Mountains, Mullets, Merica! discussed in his latest video.
To answer this question, MMM tested the cartridge's limits in an Extreme Long-Range competition. These targets varied in size—from 1 MOA to 3 MOA—and at ranges from 750 yards to 2,310 yards. For the rifle, he selected a Pristine Long Action, Outlier 26" 1/8 twist barrel, Revolutionary Arms 5-port muzzle brake, and an MDT ACC Elite chassis. To help make an impact at extreme distances, MMM chose a Leupold MK5, 5-25x56 optic with a Tremor 3 reticle. To maximize the Win Mag's potential, he loaded 220-grain Sierra Matchkings. Many factory 300 Win Mag rifles—especially older ones—will have difficulty feeding and stabilizing these heavy bullets. Modern rifles have faster twist rates and longer magazines to maximize the bullet's potential.
Most of the video's discussion focused on the rifle's performance at the ELR Match. With a voiceover of the match's first day, we gained a clear idea of what a 300 Win Mag could do when loaded with high-BC projectiles. How did MMM perform at the match? Better yet, was he able to connect at 2,310 yards with the cartridge that was introduced during the Kennedy Administration? Check out the video to find out!
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