The .224 Weatherby Magnum (5.56×49mmB) is a sporting cartridge that was developed in the 1940s by Roy Weatherby, and commercial ammunition was produced starting in 1963. At the time it was the only belted magnum varmint cartridge.^[2] It is a proprietary cartridge with no major firearms manufacturers chambering rifles for it other than Weatherby. It was originally called the .224 Weatherby Varmintmaster when it was introduced alongside the Weatherby Varmintmaster rifle, but the rifle was discontinued in 1994 and the cartridge was renamed.

The cartridge design began years earlier but its introduction was delayed, at least in part, because of the unavailability of a suitable action. An earlier high-velocity .22 caliber round from Weatherby called the .220 Weatherby Rocket was based on the .220 Swift though it was unsuccessful and never manufactured.^[3] It was the first

For more than 50 years, it was the only Weatherby cartridge to have an angled shoulder instead of the curved, double-radius shoulder found on other Weatherby cartridges. This changed in 2019 with the introduction of the RPM (Rebated Precision Magnum) family, which launched with the 6.5 Weatherby RPM^[4] and was followed in 2022 by the .338 Weatherby RPM.^[5] Both RPM cartridges have angled shoulders and, in a first for the company, a beltless design.

Performance is similar to the popular .22-250. Once Remington introduced rifles in .22-250, they quickly superseded the .224 Weatherby Magnum in popularity, forcing Weatherby to chamber rifles in .22-250. This was the first time that Weatherby offered rifles in a commercial chambering.^[6]

.22 caliber rifles are legal in some areas for big game up to the size of deer or larger. Convention holds the .224 Weatherby and similar cartridges are better suited to long-range varminting.^[7] Similar statements are made concerning other "big" 22 caliber cartridges like the .220 Swift and .223 WSSM.

Currently many states in the United States do allow 22 caliber rifles on big game, but the majority require a minimum of 6mm.^[8] Well known firearms author P.O. Ackley believed that fast 22 caliber cartridges were suitable for medium-large game.^[9] Craig Boddington has said that such cartridges are suitable for smaller deer.^[8] Bullets suited for hunting big-game are available from major manufacturers such as Nosler and Barnes.^[10]

• 5 mm caliber, other cartridges of 5–6 mm (.200–.236 in) caliber.
• List of rifle cartridges
• Table of handgun and rifle cartridges