The big bore (.45 caliber and above) AR-15 style rifle is a fairly recent phenomenon. While there are several variants, only three are what can be called actual production calibers.

The first is the 450 Bushmaster. This cartridge was originally called the .45 Professional but modified slightly when Bushmaster introduced it with Hornady making the ammunition.  It uses standard .452 caliber pistol bullets. This is the same diameter as the .45 colt handgun cartridge. It is capable of propelling a 250 grain bullet to around 2,200 fps. Both Hornady and Remington produce factory ammunition for this caliber. There is a wide selection of .452 caliber handgun bullets available from all the manufactures. However, the number of handgun bullets designed to perform at these velocities is much more limited. So, while there are a ton of bullets to choose from, very few are actually suited for this application. If you don’t have the ability to load your own ammunition, this cartridge is probably your best choice as it’s the most widely available, factory produced, big bore style for the AR platform.

The .458 SOCOM was originally conceived by members of the US Special Forces community. It was designed between 2000 and 2001. The rifle uses a lengthened 50 Action Express case necked down to hold the .458 caliber bullet.  The bolt face size used by this cartridge is identical to the very common size as used in cartridges such as the .308 Winchester. This makes it pretty universal and therefore can be chambered in many different weapons -- including bolt action rifles. The .458 caliber is a much better choice in terms of bullet selection because this is the same caliber as rifles from the  45-70 to the .458 Winchester magnum. The cartridge was designed to accommodate bullet weights of up to 600 grains, to allow for subsonic operation to use with sound suppressors. With a 300 grain bullet traveling at about 2100 fps, it can also shoot much heavier bullets than the Bushmaster. Corbon and SBR produce ammunition for this caliber. For hand loading, cases can be purchased form Starline. Finding ammunition for this caliber in your local shop is probably going to be difficult and it will likely need to be special ordered or purchased online.

The .50 Beouwulf is a proprietary cartridge produced by Alexander Arms. The case is loosely based on the .50 Action Express as well. It is based on the 7.62x39 bolt face which makes it much less adaptable to other standard rifles. This is a slightly tapered case, with no shoulder, and can easily accommodate bullets between 300 and 400 grains with even 500 grains being possible.  The .50 Beowulf is very similar in size and capacity to the .500 Smith and Wesson Magnum. It uses the same .50 caliber bullets as the Smith. The cartridge is the most powerful of the three we’ve discussed so far and can propel a 300 grain bullet at 2300 fps. The only factory ammunition is that made by Alexander Arms.  It’s not the kind of ammo you will find at your local gun shop or sporting goods store. If you are not a hand loader, it’s probably not your best choice. However, cases are easy to come by as Starline manufacturers them and they can be had from all major online firearms supply dealers.

Our review today is on the Beowulf.  We chose the Beowulf for a few reasons. The first being that it’s 50 caliber!  The Beowulf uppers are also slightly cheaper and easily available from sources such as Midway USA, which also stocks cases, bullets and loading dies.  While bullet availability of the .458 Socom is much greater than the Beowulf, everything else is less readily available.    And the reality is, thanks to the .500 Smith & Wesson, there are plenty of excellent bullets made for this rifle.

Some of the various available bullets are listed below.  There are no doubt others, and clearly these bullets, can cover any possible use.

Belt Mountain – 400 grain Punch

Barnes – 400 grain Buster solid

Hornady  - XTP 350 grain hollow point

Remington – Core Lokt 385 grain bonded

Satern – 385 grain brass solid

Sierra – 350 grain JHP

Sierra – 400 grain JSP

Speer – 300 grain total metal jacket

Speer – 325 grain JHP

Speer – 350 grain JSP

Woodleigh – 400 grain JSP

As shown above, there is a bullet available for any need one has for this weapon.

Another feature of the Beowulf is that it can use standard AR-15 magazines. No follower change is required. Occasionally, the feed lips have to be adjusted slightly but there is no need to purchase expensive proprietary magazines for this weapon. This is a feature that the .458 SOCOM also shares, as it works perfectly with standard magazines.  

The standard, 20 round, .223 magazine becomes a 5 round Beowulf magazine. The 30 round magazine becomes a 10 rounder. Alexander Arms also sells factory marked .50 Beowulf magazines. These are useful if you live in states that restrict magazine capacity to 10 rounds or less. Using a 30 round .223 magazine could run you afoul of the law, while the factory marked 10 round magazine would likely not. However, if you live in a place that restricts magazine capacity check all the local laws to ensure that these are legal in your particular area before proceeding.

All of these big bore AR cartridges are meant to deliver a heavy bullet at medium velocities. These bullets penetrate very well. Because it's a large, blunt projectile, at moderate speed, they are also short range affairs, typically less than 200 yards.

At short range, they possess immense knock down ability and also penetrate common barriers easily. This ability also makes them an ideal short range hunting cartridge. We have used the Beowulf on several hunts and its ability to take down even large game is impressive. Law enforcement and similar operators may find this type of performance useful when trying to penetrate auto glass or car bodies.

For protection against large bears, the Barnes Buster or Belt Mountain Punch bullets are ideal. They will penetrate clear through. Using Reloader 7, we easily achieved 1800 fps with these 400 grain bullets. This compares quite favorably to the very heavily loaded 45-70, (420 grain bullet at 1850 fps) lever-action rifle which is highly regarded as a excellent bear gun. No game animal would notice the difference between the two. If using Punch bullets, the advantage lies to the Beowulf since it is shooting a hard brass bullet versus the .45-70 that is shooting a hard cast lead bullet. While the hard cast bullets are excellent, based on previous testing, they can’t beat the Punch bullet in terminal performance. 

The only caveat to using the Beowulf for such critical applications (which applies to all weapons)  would be the need to shoot at least a couple of hundred rounds through the gun to make sure everything is broken in and functional. The cartridge and rifle are extremely reliable, in theory. But that reliability needs to be proven in the real world with your actual weapon before using the weapon for a critical application.

Early on, we had a few jams with the Beowulf.  However, after about the 5th magazine, everything seemed to settle down and we haven’t had any issues since. We’ve put about 500 rounds through the gun, all hand loads, and it’s quite reliable and accurate. It was easy to do 1-2 inch groups at 100 yards with the 400 grain bullets.  For testing and initial load development, we used the cheaper, Sierra 400 grain bullets. Once everything was working well, we switched to the Punch and Buster bullets.

We did no testing with the lighter bullets. We have also heard that 500 grain bullets can be used.   From our perspective, the 500 grain bullets takes up too much case volume and are still supersonic (at about 1300 fps). Therefore, they have no value as a subsonic load. We believe the sweet spot for the Beowulf is the 400 grain bullet. This cartridge is all about penetration and large caliber momentum and the 400 grain is the ticket on both counts.

All in all, this is an excellent and well-built product. Everything pretty much worked right out of the box.  If we ever need a weapon to breach barricades or smash through an engine block, this would be one of our top choices. But for us, while walking in bear country, the light weight and easy handling of our Lever Scout rifle is what we’ll likely turn to. Yes, the Beowulf is more powerful and can shoot lead a lot faster. However, since the odds of a bear encounter is so small for most, one has to weigh those odds and decide what’s best. As with everything firearms related, there is always a bigger weapon that might get the job done more reliably. But the weapon you carry all the time is going to be a lot better, in the log run, than the bazooka sitting in your safe because it’s too cumbersome to bring along.