450 Bushmaster vs. 458 SOCOM vs. 50 Beowulf: Big Bore AR Cartridges

There’s no denying that the AR-15 platform and the 223 Remington are an exceptional pair. The 223’s flat trajectory and low recoil are great for varmint hunting, plinking, and target shooting. However, the 223 lacks the kinetic energy needed for taking down larger animals like whitetail and hogs.

Adapting new calibers to the AR-15 rifle is nothing new. Cartridges like the 300 Blackout, 224 Valkyrie, 6.8 SPC, and 6.5 Grendel have all been moderately successful.

But some shooters wanted MORE POWER. Three AR-friendly thumper rounds – the 450 Bushmaster, 458 SOCOM, and 50 Beowulf – would come along to provide exactly that. All of them outdo the 223 in terms of kinetic energy (and recoil, too).

These three big bore cartridges can turn any standard AR-15 into a deer hunting rifle, a semi-automatic hog slayer, and a heavy-hitting personal defense carbine all rolled into one.

Although these rounds' terminal ballistics and effective ranges are all similar, each cartridge has its own unique advantages and disadvantages. You'd better make yourself aware of them before committing to one.

In this article we will analyze each cartridge to help you decide which thumper round will work best for your shooting needs.

Cartridge Specs

When evaluating centerfire rifle cartridges, it’s a good idea to analyze the cartridge specs to gain more knowledge of each.

The 50 Beowulf was the first of the three thumper rounds to hit the market in early 2001. The 458 SOCOM was released later that year. The 450 Bushmaster hit the market in 2007.

Not much is known about the genesis of the 50 Beowulf. Its developer Bill Alexander (of Alexander Arms) is known for keeping company matters secret.

Development of the 458 SOCOM began in 2000 following a conversation (supposedly at a barbecue) between Marty ter Weeme of Teppo Jutsu LLC and a member of the United States Special Operations Command (USSOCOM) surrounding the ineffectiveness of the 5.56 NATO round in the Battle of Mogadishu.

The 450 Bushmaster (or 450 BM) was developed by Tim LeGendre of LeMAG. LeGendre cites Lt. Col. Jeff Cooper’s writings on the thumper concept as his inspiration for the 450 BM.

Perhaps the biggest difference between these three cartridges are their case designs . The 450 Bushmaster and 50 Beowulf are both straight-walled cartridges, whereas the 458 SOCOM has a slight shoulder. A straight-walled cartridge is necessary for deer hunting in Midwest states like Ohio, Iowa, Indiana and Michigan. The bottlenecked design aids in reliable feeding.

Although developed under different circumstances, both the Beowulf and the SOCOM share the same parent case: a lengthened 50 Action Express (50 AE; best known for its appearances in Desert Eagle handguns). The 50 Beowulf has a longer case at 1.65” compared to 1.575” for the 458. In contrast, the 450 Bushmaster was developed using the 284 Winchester as a parent case and has the longest case at 1.70”.

Although their case lengths are different, the 450 Bushmaster and 458 SOCOM have the same maximum overall length of 2.26” (the longest an AR-15 receiver can manage). The 50 Beowulf's maximum overall length is 2.25”.

All three rounds have a rebated rim design, meaning their rims are narrower than their bases. The 450 BM and 458 SOCOM have the same rim diameter of 0.473”, which is the same as the 308 Winchester, 30-06 Springfield, and 270 Win. In contrast, the 50 Beowulf has a 0.447” diameter rim – the same as the 6.5 Grendel (another round made by Alexander Arms).

Another major difference between all three cartridges is the type of bullet each fires. The 50 Beowulf fires a 0.50” diameter bullet (like the 500 S&W Magnum and 50 AE). Beowulf ammo comes in bullet weights ranging between 200 and 600 grains, though 335, 350, and 400 grain bullets are the most common.

The 458 SOCOM fires a 0.458” diameter bullet, which is much more common, as this bullet diameter is used by .45-70 Government, 458 Winchester Magnum, 450 Marlin, 460 Weatherby, and 458 Lott. The SOCOM round can fire bullets within the same 200-600 grain range, though 250, 300, and 350 grain factory loads are the most common.

Lastly, the 450 Bushmaster fires 0.452” diameter bullets ranging 158 to 300 grains (with 250 and 260 grains being most popular). In contrast, the 458 can fire bullets between 200 to 600 grains, with 250, 300, and 350 grains being more common.

All three rounds are generally loaded to similar pressures, but the 450 Bushmaster is the only SAAMI certified cartridge of the three with a listed maximum pressure of 38,500 psi. Note that the "50 Beowulf" name is trademarked by Alexander Arms. To avoid any potential trademark litigation, ammo manufacturers often brand their 50 Beowulf ammo by its metric designation: 12.7x42mm.

Muzzle Velocity, Kinetic Energy, and Trajectory

Lt. Col. Jeff Cooper defined the “thumper concept” as a cartridge designed to be fired from the semi-auto AR-15, with an effective range of around 250 yards, a .44 caliber or wider bullet, and the capacity to reliably harvest large game in one shot.

All three of these rounds fit the bill in terms of integrating into the AR-15 platform and being larger than .44 caliber – but how do they stack up in terms of ballistics?

For the purpose of this comparison, we will analyze the ballistic performance of the 250 grain Hornady FTX for 450 Bushmaster, the Barnes 300 grain TTSX loaded by Buffalo Bore for 458 SOCOM, and the 350 grain XTP jacketed hollow point loaded by Underwood for 50 Beowulf.

In the chart below, we will compare muzzle velocity, kinetic energy, and bullet drop for each cartridge assuming a 100-yard zero.

The 450 Bushmaster dominates in terms of muzzle velocity, as its bullet leaves the barrel at a whopping 2,200 fps – 300 fps faster than the 458 SOCOM, and 425 fps faster than the 50 Beowulf. Its high muzzle velocity gives the 450 Bushmaster a flatter trajectory out to 250 yards, although the 458 SOCOM is a very close second in terms of bullet drop.

In terms of muzzle energy, the 450 Bushmaster continues to outperform at 2,687 ft-lbs, followed by the 50 Beowulf at 2,448 ft-lbs, with the 458 SOCOM bringing up the rear at 2,405 ft-lbs.

Although there are minor differences between these three rounds, all have similar trajectories out to 150 yards. The trajectory of the 50 Beowulf drops off considerably past 150 yards as the bullet goes subsonic at this range. On the other hand, the 450 Bushmaster and 458 SOCOM can remain supersonic past 300 yards.

Hunters generally consider 1,000 ft-lbs of kinetic energy the minimum required for harvesting a whitetail. For elk, it's higher at 1,500 ft-lbs. This means that the 50 Beowulf's effective range for deer is around 150 yards and 100 yards for elk. In contrast, the 450 Bushmaster and 458 SOCOM have an effective range of 250 yards for deer and 150 yards for elk (all approximate).

Recoil

There’s a reason why this class of rifle cartridges is known as “thumper rounds”. Not only do they hit hard on large game, but they impart stout recoil on the shooter’s shoulder as well.

Felt recoil differs from shooter to shooter and is dependent on shooting position, stance, and the firearm being used. However, free recoil can be used to give an objective sense idea of how hard a round kicks.

Free recoil is dependent on bullet weight, rifle weight, muzzle velocity, and powder charge weight. To provide a clean apples-to-apples comparison, a standard AR-15 carbine weight (7.5 lbs) will be used for each calculation.

This may not be completely accurate in terms of real-world experience, as 50 Beowulf rifles are generally a little heavier than 450 Bushmaster rifles. However, the chart below will give you a general idea of how much recoil each cartridge imparts on the shooter.

It should be noted that none of these cartridges would be described as having "low recoil." However, because the 450 Bushmaster fires lighter bullets, it also has less recoil than the 458 SOCOM and 50 Beowulf.

Ballistic Coefficient and Sectional Density

Ballistic coefficient (BC) is a measure of how aerodynamic a bullet is and how well it will resist wind deflection. Sectional density (SD) is a way to evaluate the penetration ability of a bullet based on its diameter and weight.

In the table below we listed the ballistic coefficients and sectional densities for our selection of three rounds.

The 458 SOCOM has the highest ballistic coeffieicnt at 0.236, followed by the Bushmaster at 0.210 and the Beowulf at 0.150.

Longer and heavier bullets typically have higher BCs, as they resist wind drift more efficiently than shorter, heavier ones. The 50 Beo has the heaviest bullet of the three, but it also has the lowest BC due to its bullet design.

These rounds' capabilities are restricted by the AR-15 platform. Restricting the maximum overall length of a cartridge to 2.26” and demanding kinetic energy values over 2,000 ft-lbs means that bullet design must take a back seat to external ballistics. Therefore, short and thick bullets have to be used instead of more aerodynamic alternatives.

In terms of penetration, the Beowulf and SOCOM are essentially tied with sectional densities of 0.200 and 0.204, respectively. The Bushmaster comes last at 0.175.

It is unlikely that the whitetail or hog in your sights will be able to detect any differences in penetration. Even so, objectively speaking, the 458 and 50 bullets are equipped to penetrate just a bit deeper than the 450.

50 Beowulf vs. 458 SOCOM

The 50 Beowulf fires wider and heavier bullets than the 458 SOCOM. Although it fires a lighter bullet, the 458 SOCOM has a maximum effective range of around 250 yards on large game. The less efficient bullet design of the Beowulf limits its effective range to 150 yards. The 50 Beowulf also has higher recoil.

450 Bushmaster vs. 458 SOCOM

The 450 Bushmaster and 458 SOCOM have similar ballistic performance out to 250 yards, which is the maximum effective range for both rifle cartridges. However, the 450 Bushmaster has a flatter trajectory as it fires lighter bullets at higher muzzle velocities. The 458 SOCOM also has slightly more recoil.

450 Bushmaster vs. 50 Beowulf

The 450 Bushmaster has higher muzzle velocity, more kinetic energy, and a longer effective range than the 50 Beowulf. The 50 Beowulf has about 25% more free recoil than the 450 Bushmaster, but the Beowulf also has higher sectional density.

Hunting

When it comes to big game hunting, all three cartridges are excellent options within their effective ranges.

The 450 Bushmaster and 50 Beowulf are excellent deer hunting options in states that require the use of straight-walled cartridges. On the other hand, the 458 SOCOM offers similar ballistic performance to the 450 Bushmaster with heavier bullets.

The primary limiting factor for the 50 Beowulf is its shorter effective range. For elk, the Beowulf is limited to 100-yard shots, and 150 yards for deer. Although the 50 Beo fires the widest bullet of the three, its aerodynamically inefficient bullet hemorrhages velocity and kinetic energy downrange, and has gone completely subsonic by 200 yards.

With the 450 and 458, elk can be taken safely within 150 yards, and whitetail can be ethically harvested at 250 yards. That's why many hunters prefer the 450 Bushmaster and 458 SOCOM, as they allow the harvesting of game at longer ranges.

All three rounds are excellent choices for hogs, coyotes, and general pests. However, hunters generally favor the 223 Remington for varmint control for its lower price point and flatter trajectory.

Ammo and Rifle Cost/Availability

Of the three rounds, the 450 Bushmaster is the easiest to find factory ammo for. It is SAAMI certified, and big names like Hornady, Remington, Winchester, Barnes, and Federal therefore produce it. On the other hand, only custom ammo manufacturers like Underwood, Buffalo Bore and Black Butterfly make 458 SOCOM and 50 Beowulf rounds.

For 450 Bushmaster ammo, inexpensive Remington UMC factory loads can be had for as low as $1.50/round, while premium hunting ammo like Federal Fusion or Barnes VOR-TX costs around $3/round and up.

For the 458 SOCOM, less expensive factory loads from Underwood Ammo can be had for around $2/round, while bear hunting hard cast loads from Buffalo Bore run upward of $5/round.

Most of the factory ammo for 50 Beowulf comes from Alexander Arms, as they hold the trademark on the cartridge name. However, custom ammo manufacturers often make their own 50 Beowulf loads under the metric designation 12.7x42mm. Factory ammo from Alexander Arms will run you around $1.70/round, while custom ammo for hunting or personal defense typically cost around $3/round.

In terms of rifle availability, there are considerably more options for 450 Bushmaster compared to 458 SOCOM or 50 Beowulf.

For the 458, the most common options available are AR-15 rifles from manufacturers like Tromix, Wilson Combat, and Bear Creek Arsenal (BCA). Alexander Arms is the primary supplier of all rifles, parts, and upper receivers for the 50 Beowulf, though BCA is another option at a lower price point. 

Since the 450 is SAAMI certified, there are considerably more rifle options for it – including bolt-action rifles like the Ruger American and Savage 110.

However, as any AR-15 rifle is a potential host with a simple barrel, bolt, and magazine change, this means there are a lot of potential rifles on the market for all three cartridges.  

Reloading

As factory loads can be a little pricey for these big bore AR rounds, handloading is one method shooters utilize to reduce their overall cost per round.

All of the major bullet manufacturers including Barnes, Hornady, Nosler, Sierra, and Federal have multiple bullet options available for all three calibers. This gives handloaders the flexibility to create rounds that are customized to their rifles and unique shooting needs.

Sourcing reloading dies is fairly simple for each cartridge. Lee Precision and Redding both have die sets for each round.

It is not advised to use 45 ACP handgun bullets for reloading the 450 Bushmaster. Jacketed 45 ACP bullets measure 0.451” in diameter. The 450 Bushmaster requires slightly wider 0.452” diameter bullets. Although the smaller 0.451” diameter bullets can be handloaded safely, you will likely see decreased performance and accuracy as the bullet may not completely engage the rifling in the barrel.

Final Shots: 450 Bushmaster vs. 458 SOCOM vs. 50 Beowulf

The 450 Bushmaster, 458 SOCOM, and 50 Beowulf are three big bore cartridges that add a lot of stopping power to the AR-15 rifle. Designed for shots within 250 yards or less (<150 yards for the Beowulf), these three rounds deliver crippling kinetic energy that can transform any AR-15 into a capable hog and deer hunting rifle.

The 450 Bushmaster and 50 Beowulf are excellent deer hunting options for Midwest states that require the use of straight-walled cartridges. The 450 Bushmaster is also unique in the fact that there are single shot and bolt-action rifles available for hunters that are required to use these firearms whereas the 458 and 50 are relegated to the AR-15 platform only.

For larger game like elk, black bear, and even moose, I’d favor the 458 SOCOM primarily due to the Barnes 300gr TTSX bullet the round was specifically designed for. This bullet is absolutely devastating on large game so long as your shot placement is on point.

Selecting the right thumper round for your needs primarily revolves around your local hunting regulations, the type of game you want to hunt, and the ranges you expect to shoot at.

Regardless of which cartridge you choose, make sure you get all your ammunition here at Ammo.com and get out to the range so you are always ready to defend freedom should the need arise.