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There’s no denying that the pairing of the AR-15 platform and the 223 Remington is an exceptional match. The 223’s flat trajectory and low recoil is great for varmint hunting, plinking, and target shooting; however, it 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, and cartridges like the 300 Blackout, 224 Valkyrie, 6.8 SPC, and 6.5 Grendel have all been moderately successful.
But some shooters wanted more…they wanted more muzzle energy, more fps, more stopping power.
And for those shooters who just want MORE, this trifecta of Thumper rounds can provide all the kinetic energy and recoil your heart could desire – the 450 Bushmaster, 458 SOCOM, and 50 Beowulf.
These three big bore cartridges give you the flexibility to turn a standard AR-15 into a deer hunting rifle, a semi-automatic hog slayer, and a heavy-hitting personal defense carbine all rolled up into one firearm.
Although the terminal ballistics and effective range of all three rounds are similar, each cartridge is unique and has its own advantages and disadvantages that shooters need to weigh before upgrading their AR-15.
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 although the 458 SOCOM was released shortly after in the same year while the 450 Bushmaster was released in 2007.
Developed by Alexander Arms, not much is known about the genesis of the 50 Beowulf as Bill Alexander is known for keeping company matters a closely guarded secret.
On the other hand, development of the 458 SOCOM began in 2000 in response to 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) surrounding the ineffectiveness of the 5.56 NATO round in the Battle of Mogadishu in 1993.
The 450 Bushmaster (or 450 BM) was developed by Tim LeGendre of LeMAG Firearm. LeGendre cites Lt. Col. Jeff Cooper’s writings on the Thumper concept as his inspiration for creating the 450 BM.
Perhaps the biggest difference between these three cartridges is their case design itself. The 450 Bushmaster and 50 Beowulf are both straight-walled cartridges while 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 while 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, or 50 AE, was utilized for both cartridges, though the 50 Beowulf has a longer case at 1.65” compared to 1.575” for the 458. The 50 AE is most well-known for being the primary chambering of the Desert Eagle handgun. In contrast, the 450 Bushmaster was developed using the 284 Winchester as a parent case and has the longest case length at 1.70”.
More:
https://ammo.com/comparison/450-bushmaster-vs-458-socom-vs-50-beowulfFor hunting I chose the 6.5 Grendel and the .358 Yeti.
358 Yeti
The .358 Yeti is a mid-bore wildcat being developed for the AR-15 platform with the balance of speed and power in mind. It is based off plentiful 7.62x51 NATO brass shortened to 1.646" and resized to accommodate a .358 diameter projectile. The choice to use NATO brass for the parent case is because it has the thickest case wall, meaning that any other brass with the .473" head will be useable (i.e. .308, .243, 7mm-08, 6.5CM, etc). This gives the end user many sources for very affordable (and sometimes free) brass. The chamber has been designed with brass making in mind meaning there is no neck turning or reaming necessary. Simply chop the brass at the neck/ shoulder junction, run through a sizing die, final trim, and chamfer/ debur –much like the 277 Wolverine. Formed cases will hold 45-47g of h2o with a slight increase of capacity being gained once fired, but this round not one to be classified as “requiring fire-forming.”
The performance goals for this cartridge are to get a 180g projectile up to 2600fps from a 16"-18" barrel and a 200g to 2500fps. At those anticipated velocities, the 358 Yeti will generate more energy than the following calibers: 6.8 SPC, 300 Blackout, 450 Bushmaster, 458 SOCOM, 50 Beowulf, 35 Remington, and 6.5 Grendel (*up to 375 yards).
Useable projectiles are in the 180g-225g range with the option of lighter projectiles such as those for 38/357 and 9mm as well for inexpensive rounds for plinking. The 358 Yeti is designed to have optimal performance with projectiles in the 180-200g range such as the Speer Hotcor, Hornady interlock, and Hornady FTX. Some Barnes and Nosler offerings are also possible with the removal of the polymer ballistic tips. Additionally, 250g+ projectiles will be tested for subsonic performance.
