12.7x42 (.50 BEO) Uppers

.50 Beowulf Upper: The What and The Why

Known for its massive power, there’s a reason why this caliber got its name from the old heroic legend. The .50 Beowulf caliber is truly a force to be reckoned with.

Developed by Alexander Arms sometime around 2001, its primary purpose of design is to greatly improve the effectiveness at short to medium ranges when compared to the 5.56/45mm NATO.

We’ll take a look at what makes the .50 Beowulf upper complete. We’ll talk about the characteristics of the caliber, as well as the .50 Beowulf upper, and how you can make it into your own AR-15.

What’s the .50 Beowulf?

The .50 Beo is a 12mm caliber cartridge that’s designed to be one of the most devastating bullets fired from an AR-15.

As mentioned, the .50 Beowulf round is simply built for stopping power that can be made compact into an AR-15 platform with a 50 Beowulf upper receiver.

With its tapered cartridges and a rebated case rim, the .50 Beo can work with a 7.62×39 mm bolt face.

The monster who is killed by the epic hero, Beowulf, is named Grendel; another cartridge developed by Alexander Arms. The .50 Beowulf cartridge has a rebated rim that matches the 6.5 Grendel rim. Makes sense now, does it?

Size, Design, and Hunting Purpose

Keep in mind the .50 Beowulf cartridge is short, but it doesn’t double stack like the 5.56 NATO. The Alexander Arms .50 Beowulf complete upper has an enlarged ejection port for this reason.

Most hunters would think twice before browsing a 50 Beowulf upper for sale, but they would definitely check first to see if it has all the right characteristics, like barrel and twist.

Take, for example, the MSF 16” 12.7×42 Upper Receiver Assembly;  This 12.7×42 upper complete with all the necessary components, is a surefire way to let the stopping power do its own thing, especially when hunting deer.

What About Pistols?

The dreaded 50 Beowulf Complete Upper can also be used as a shorter platform – a short-barreled rifle.

Still, you’ll have to obtain your ATF tax stamp if you want to go for the 12.7×42 pistol upper with an adjustable stock.

What Is It Good For

For Hunting

The reason why the .50 Beowulf caliber has grown so popular throughout the 2000s is because of its immense stopping power, especially when used through a 12.7×42 complete upper.

Hunters of all types always keep a round such as this. It’s widely recognized as a standard bullet for hunting North American game like moose and deer.

Home Defense

While it’s great for hunting, a 12.7 x 42 upper with a .50 Beowulf is definitely not great for home defense because a 5.56 NATO AR-15 platform is much better because you don’t need that much power to stop a human assailant.

There’s a reason why .50 Beowulf bullets work best for hunting deer, bears, elk, and moose.

AR-15 in .50 Beowulf: Is It Possible?

If your AR-15 platform with a .50 Beowulf AR upper has the right ammo, good optics, a flashlight, and a proper suppressor, you have yourself an ideal rifle.

However, if you’re planning to go on your own, you will first need to find a 50 Beowulf upper complete barrel with a proper bolt carrier, and compatibility for the 7.62×39 mm rebated cartridge rim.

Many of the new 50 Beowulf uppers always come in 16.5-inch barrels, but some folks also prefer the 12-inch 50 Beowulf AR upper.