450 Bushmaster vs. 458 SOCOM: Some Shooters Like It Bigger

First Shots: 450 Bushmaster vs. 458 SOCOM

Do you want to fire beefier ammo in your AR-15 than 5.56 NATO? Then you must be a shooter of culture – the kind of cat who would truly appreciate the .45 caliber. I like that!

That just begs the question: which .45 cal AR round should you choose? The 450 Bushmaster? Or the 458 SOCOM?

Both big bore cartridges give you the flexibility to turn a standard AR-15 into a proper deer rifle, a semi-automatic hog slayer, and a heavy-hitting personal defense carbine all rolled up into one.

In this article we will analyze each cartridge to help you decide which one you should prefer.

Cartridge Specs

When comparing two cartridges, it's good to begin with their physical specifications.

The 458 SOCOM was the first thumper round, hitting the market in 2001. The 450 Bushmaster reached store shelves six years later.

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 (SOCOM), the latter of whom spoke of the ineffectiveness of the 5.56 NATO. He explained that members of Task Force Ranger were dissatisfied with the 5.56's terminal performance during the Battle of Mogadishu. Those complaints are ultimately what initiated development of the 458 SOCOM.

The 450 Bushmaster (450 BM) was developed by Tim LeGendre of LeMAG Firearms. LeGendre cites Lt. Col. Jeff Cooper's "thumper" concept (i.e. a .44+ cal semi-automatic rifle cartridge capable of one-shotting big game at 250 yards) as the inspiration for the 450 BM.

Perhaps the biggest difference between these two cartridges are their case designs. The 450 Bushmaster is a straight-walled cartridge, whereas the 458 SOCOM has a slight shoulder. Straight-walled cartridges are necessary for deer hunting in Midwest states like Ohio, Iowa, Indiana, and Michigan – part of the driving force behind the 450 BM's popularity. In addition to facilitating feeding, a bottleneck case allows a cartridge to store more propellant relative to the size of its bullet. In other words, a bottleneck case (such as the 450 BM's) helps a cartridge be more powerful.

Although developed to achieve similar ballistic results, the 458 SOCOM and 450 Bushmaster have very different parent cases. The 458 SOCOM sports a 50 Action Express (50 AE) case lengthened to 1.575”. (The 50 AE is best known as the primary chambering of the Desert Eagle handgun.) In contrast, the 450 Bushmaster's parent case is a shortened 284 Winchester (though at 1.700”, the 450 BM's case is longer than the 458 SOCOM's).

Although their case lengths are different, the 450 Bushmaster and 458 SOCOM have the same maximum overall length of 2.26”. That is not by happenstance, as 2.26” is the longest cartridge length an AR-15 receiver accepts. These two big bore cartridges case capacities are almost identical. The 450 can hold 59.5 grains H2O; the 458 SOCOM, 61.1 grais H2O.

Both rounds' cases have a rebated rim, meaning their rims are narrower than their bases. The 450 BM and 458 SOCOM share a rim diameter of 0.473” – same as the 308 Winchester, 30-06 Springfield, and 270 Win.

One major difference between the cartridges are the types of bullets they fire.

The 458 SOCOM fires a 0.458” diameter bullet. That's more common than you might think, as it is also used by rounds such as the 45-70 Government, 458 Winchester Magnum, 450 Marlin, 460 Weatherby, and 458 Lott. The 458 SOCOM round can fire bullets within a 200-600 grain range, with 250, 300, and 350 grain factory loads being most common.

In contrast, the 450 Bushmaster fires a 0.452” diameter bullet, ranging 158 to 300 grains (with the 250 grain bullet being the most popular, with 260 grains coming in close at second). Bullets fired by the 450 Bushmaster are also fired by three popular handgun cartridges: 45 Colt, 454 Casull, and 460 S&W.

Both rounds are loaded to similar pressures, but only the 450 Bushmaster is SAAMI certified with a listed maximum pressure of 38,500 psi.

Muzzle Velocity, Kinetic Energy, and Trajectory

Both of these rounds meet the criteria for Lt. Col. Cooper's thumper concept. But how do they compare ballistically?

Let's compare the ballistic performance of the 450 Bushmaster 250 grain Hornady FTX and 300 grain Federal Power-Shok soft point. For the 458 SOCOM, the 300 grain Barnes TTSX and 450 grain FMJ load by SBR Precision Ammunition.

The chart below compares muzzle velocity, kinetic energy, and bullet drop for each cartridge out to 300 yards (assuming a 100-yard zero).

Although the 458 SOCOM has slightly higher case capacity, the 450 Bushmaster's lighter bullets typically achieve higher muzzle velocities. The 450 BM 250 grain FTX has the fastest muzzle velocity on the chart: 2,200 fps. Both 300 grain loads share a muzzle velocity of 1,900 fps. Not unsurprisingly, the 450 SOCOM's heavyweight 450 grain FMJ has the lowest muzzle velocity at 1,450 fps.

In terms of muzzle energy, the 450 Bushmaster 250 grain FTX continues to outperform at 2,687 ft-lbs. Both rounds' 300 grain bullets possess 2,405 ft-lbs of kinetic energy at the muzzle. The 458 SOCOM's 450 grain bullet "only" has 2,101 ft-lbs.

Although there are minor differences between these four rounds, all of them exhibit similar trajectories out to 150 yards. The difference becomes clearer beyond 200 yards, where the 458 SOCOM sheds velocity at a much faster rate than the 450 BM. At 300 yards, the 250gr FTX and 300gr TTSX loads are still supersonic (barely), while the 300gr soft point and 450gr FMJ loads have dipped below the speed of sound.

It should be noted that neither of these rounds are incredibly flat shooting. However, the lighter 450 Bushmaster loads give you the flatter trajectories, and typically stay supersonic past 300 yards.

Hunters generally consider 1,000 foot-pounds of kinetic energy the minimum amount required for harvesting a whitetail, and 1,500 foot-pounds the minimum for elk or other large game. With this in mind, the 450 Bushmaster and 458 SOCOM have an identical effective range of 250 yards for deer and 150 yards for elk.

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 and ammo being used. Conversely, free recoil is totally objective. It is determined by four factors: bullet weight, rifle weight, muzzle velocity, and propellant charge weight.

In general, the 450 Bushmaster has slightly less recoil than the 458 SOCOM. However, the difference is slight enough that most shooters won’t be able to discern any difference between the two.

The bottom line is that both cartridges have heavy recoil, and are not suitable for recoil-sensitive shooters who haven't received proper training and acclimatization.

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 measure of how effectively a bullet penetrates flesh, and is determined by two factors: bullet diameter, and bullet weight.

Restricting maximum overall cartridge length to 2.26” and necessitating muzzle velocity in excess of 2,000 ft-lbs requires bullet design to take a back seat to external ballistics. The design criteria the 458 SOCOM and 450 BM had to satisfy are why both have short and thick bullets – not the long, narrow, and overall more aerodynamic ones which typically achieve higher BCs.

Generally, the 458 SOCOM has a higher BC than the 450 Bushmaster, as it can fire heavier bullets. For example, the 458 SOCOM 300gr SST has a G1 BC of 0.236; the 450 Bushmaster 250gr XTP, 0.210.

In terms of sectional density, the 458 SOCOM measures higher: 0.204, compared to 0.175 for the 450 BM. In other words, the 458 SOCOM bullet is more effective at penetrating ita target, and therefore more inclined to inflict a deeper wound column. (Even so, it is unlikely that the whitetail or hog in your sights will be able to detect any differences in penetration.)

Hunting

When it comes to big game hunting, the 458 SOCOM and 450 Bushmaster are excellent options within their effective range.

For larger game like elk and moose, the 458 SOCOM makes more sense. It fires a wider bullet, thereby increasing the size of the wound channel. It's just an incredibly hard-hitting cartridge.

For hogs, coyotes, and pests, you can’t go wrong with either cartridge. The 458 SOCOM is typically favored for feral hogs. The 450 BM is more than lethal enough for hogs, although hunters typically don’t restrict themselves to straight-walled cartridges unless they have to.

Neither the 450 Bushmaster nor 458 SOCOM is particularly useful for varmint hunting due to their heavy recoil. That’s not to say that you CAN’T use them for this purpose, although most hunters prefer something with lower recoil for these pesky critters. Rounds like the 223 Remington are usually preferred for varmint hunting because they have low recoil, flat trajectories, and lower price tags.

Ammo and Rifle Cost/Availability

When it comes to ammo availability, you cannot beat the 450 Bushmaster. It is easier to find factory ammo for, as it is SAAMI certified and larger ammo manufacturers like Hornady, Remington, Winchester, Barnes, and Federal all produce it. On the other hand, only custom ammo manufacturers like SBR, Underwood, Buffalo Bore, and Black Butterfly regularly make 458 SOCOM rounds. Naturally, being rarer means that 458 SOCOM is also more expensive.

In terms of factory rifle availability, there are considerably more options for the 450 Bushmaster compared to the 458 SOCOM.

For the 458 SOCOM, the most common options available are AR-15 rifles by manufacturers like Tromix, Wilson Combat, and Bear Creek Arsenal. Since the 450 BM is SAAMI certified, there are considerably more rifle options available, including bolt-action rifles like the Ruger American and Savage 110.

Of course, since converting an AR-15 to fire either round only requires a barrel, bolt, and magazine swap, your options are virtually limitless regardless of which one you adopt.

Reloading

Since factory loads can be a little pricey for these big bore AR rounds, handloading them is a popular cost-safing method.

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

Sourcing reloading dies is simple enough. Lee, Redding, and others offer die sets for each round.

It should be noted that it is not advised to use 45 ACP handgun bullets for reloading the 450 Bushmaster. Jacketed 45 ACP bullets measure 0.451” in diameter, while 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 such bullets may not completely engage the rifling in the barrel.

Final Shots: 450 Bushmaster vs. 458 SOCOM

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

The 450 Bushmaster is an excellent deer hunting option for Midwest states that require the use of straight-walled cartridges. Single-shot and bolt-action rifles chambered for 450 BM are available. If you choose the 458 SOCOM, you will be required to fire an AR platform rifle.

For big game like elk, black bear, and moose, I’d favor the 458 SOCOM loaded with the Barnes 300gr TTSX bullet. This bullet is absolutely devastating to 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.

Written by

Chris Dwulet