Skip to main content

The Biggest AR Ever: NEMO OMEN .458 Winchester Magnum

The Biggest AR Ever: NEMO OMEN .458 Winchester Magnum

nemo_458_1It is no secret I like big-bore rifles. I also like ARs. So far, these two obsessions have been rather mutually exclusive. In an attempt to eke more horsepower out of the AR platform, I was an early adopter of the 6.8 SPC, .458 SOCOM, and the .338 Federal in my Elmer Keith-like obsession for a powerful AR. And while all of these calibers have their niches, I always lusted for more. Enter NEMO.

Known for precision, military-tough arms, NEMO rocked the shooting world two years ago by introducing the TiONE (an all titanium one-off AR designed to showcase their manufacturing capabilities) followed by a magnum-sized AR action large enough to handle the .300 Win. Mag. They fittingly named it the OMEN.

After seeing this extra-large action, my wheels began to turn. So when I met Clint Walker, NEMO's cofounder, I posed the question that had been bouncing around my cluttered brain: "Why not use an OMEN action to build a .458 Win. Mag.?"

Unlike my fantasy approach to firearm manufacturing, NEMO bases its product development decisions on a rifle's usefulness for military operators.


Clint's simple and very valid response was, "Why?"


"Why? Why not? Who wouldn't want a 10-shot semiauto .458 Win. Mag?" I asked. "Hell, man, every red-blooded Texan would buy at least two — one for his pickup and one for his wife's SUV."

I joked, but at the same time was more than half serious. If I wanted one, there had to be some other crazy rednecks who would feel the same.

nemo_458_2In all seriousness, a .458 Win. Mag. AR would have some serious advantages in the hunting world. The NEMO offers a capacity of more than twice its nearest bolt-action competitor, piston-driven reliability, reduced gas-operated recoil, and durability that could stand up to the harshest hunting conditions.

Bear, moose, and nilgai hunters would swoon. Alaskan guides who want the ultimate brown bear backup rifle would welcome the offering. While unconventional for an African safari, I can't think of a more effective Cape buffalo rifle, though getting a semiauto into most African countries can run the gamut from problematic to impossible.


After thinking it over, Walker put me in touch with Josh Sonju, NEMO's cofounder and vice president of research and development.

"Yes, I think we could do that," he said. "I hunt with ARs all the time and built an OMEN in .338 Win. Mag., so a .458 Win. Mag. shouldn't be a problem."

Several months later, I received the gun. I would like to say it's a one-off, but Josh was bitten by the big-bore bug (I knew there were other like-minded rednecks out there) and built a second for himself.


The Specs

Tipping the scales at 12.4 pounds, this is no small rifle. Then again, when shot-putting 500-grain slugs downrange at 2,090 fps, I am not a fan of light rifles anyway. More importantly, this rifle balances well. Even with a magazine loaded with 10 rounds of Federal 500- grain Fusion and an Aimpoint PRO atop for a total combined weight of 14.5 pounds, it still balances comfortably and directly in the hands.

nemo_458_4The 18.5-inch 416 stainless barrel with its black Cerakote is impervious to harsh conditions. The upper and lower receivers are both hard anodized tan with black accents.

Shooting The Beast

The rifle was even more impressive on the range. Most onlookers said, "I bet this will knock your fillings out," but most of those guys have never shot a true big-bore rifle. I have shot a ton of .458 ammo through a lot of different rifles, and this one is easily the most comfortable. There are three main reasons: the large brake on the muzzle, the gas system, and the physical weight.

Conclusion

Overall, the NEMO was no surprise in the construction department. I have shot several NEMO rifles in the past, and all of them have been consistently well made. The caliber itself was a surprise. Getting a straight-walled case with pretty blunt bullets to feed in a semiauto is no easy task, but Josh modified their standard magazine followers and got it to work well.

nemo_458_3In our tests, we had minimal failure, with both Federal Fusions and Federal Premium Hydro Solids. With a little breaking in, load experimentation, and fine tuning the gas system, I believe this rifle would be as reliable as most other dangerous game offerings.

What's next? The doors are literally wide open for NEMO and hunting ARs. Obviously, the long-range big-game crowd is covered with NEMO's flagship .300 Win. Mag. Creating a .338 Win. Mag. is no problem, and as we have just discovered, the biggest of the Winchester Magnum family is also within the realm of possibility.

While .375 H&H is out due to its overall length, at first glance it appears that the .375 Ruger and .416 Ruger would fit inside a NEMO magazine and work within the pressure parameters just fine. Josh seems to agree, so who knows, there may be another big-game NEMO offering just over the horizon.

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Recommended Articles

See More Recommendations

Popular Videos

New for 2021: Nosler M48 Mountain Carbon Rifle New Chamberings, Stock Updates

New for 2021: Nosler M48 Mountain Carbon Rifle New Chamberings, Stock Updates

Regardless of which caliber or color scheme option you choose, these M48 Carbon Rifles are the perfect way to get into a hard-hitting, affordable, lightweight, accurate, and high precision rifle from Nosler.

Venison Curry Recipe

Venison Curry Recipe

Hearty and flavorful, this curry is simple to make and requires just a few ingredients you can likely find at your local store. The cooking method turns tough cuts tender, making it a great choice for shoulder and hindquarter cuts from deer, elk and other venison. Bonus points if you use axis deer, which are native to India.

Stuffed Elk Backstrap Recipe

Stuffed Elk Backstrap Recipe

Take your venison loin to a whole new level with this delicious reverse-seared stuffed elk backstrap. Smoking the backstrap on a Camp Chef Woodwind pellet grill first, then finishing it on a blazing-hot skillet or flattop, creates a perfectly cooked, medium-rare steak with a crispy, seared exterior. The filling of diced mushrooms and creamy Boursin cheese adds a whole new level of amazing flavors to an otherwise classic smoked venison loin.

New for 2021: Browning X-Bolt Pro McMillan & Recoil Hawg

New for 2021: Browning X-Bolt Pro McMillan & Recoil Hawg

Browning's X-Bolt Pro family has grown in 2021 with the addition of the Pro McMillan. An innovative muzzle break — the Recoil Hawg — also joins the line.

See More Popular Videos

Trending Articles

The famous gunmaker – Springfield Armory – stakes its first flag in the hunting world with the new, feature-packed Model 2020 Waypoint bolt-action rifle.New Springfield Model 2020 Waypoint Rifle is a Must-See Guns

New Springfield Model 2020 Waypoint Rifle is a Must-See

Petersen's Hunting Staff - September 29, 2020

The famous gunmaker – Springfield Armory – stakes its first flag in the hunting world with the...

The new Moultrie X-6000 series cellular trail camera and the Moultrie Mobile app are redefining remote and low-impact scouting. Here's why and how one or a network of them can help you.Is a Cellular Trail Camera Right for You? Accessories

Is a Cellular Trail Camera Right for You?

Josh Honeycutt - September 15, 2020

The new Moultrie X-6000 series cellular trail camera and the Moultrie Mobile app are...

Crossbow technology, accuracy and power continue to advance with demand, and this year's crop is the most impressive yet; here's a look at the top five that caught our eye.Ranking the 5 Best Crossbows for 2020 Bowhunting

Ranking the 5 Best Crossbows for 2020

Chris Larsen - September 21, 2020

Crossbow technology, accuracy and power continue to advance with demand, and this year's crop...

Is lever-action rifle dead? Not by a long shot; everything old is new again as classic lever guns find popularity among nostalgic hunters.The Return of Lever-Action Rifles Guns

The Return of Lever-Action Rifles

Craig Boddington - June 27, 2020

Is lever-action rifle dead? Not by a long shot; everything old is new again as classic lever...

See More Trending Articles

More Guns

Get young shooters started right with the perfect rimfire rifle. The 4 Best Youth Rifles Guns

The 4 Best Youth Rifles

Keith Wood

Get young shooters started right with the perfect rimfire rifle.

It's a cause for celebration when you pair today's brand new rifles with two of the most popular cartridge options.New 6.5 and .300 PRC Rifles for 2021 SHOT Show

New 6.5 and .300 PRC Rifles for 2021

Anthony Licata - February 02, 2021

It's a cause for celebration when you pair today's brand new rifles with two of the most...

What to look for when buying a gun for hunting any type of deer.How to Pick a Deer Rifle Guns

How to Pick a Deer Rifle

Craig Boddington

What to look for when buying a gun for hunting any type of deer.

This rifle offers the features of higher-grade guns without all of the cost.Bergara B14 Wilderness Ridge .300 PRC: Rifle Review Guns

Bergara B14 Wilderness Ridge .300 PRC: Rifle Review

Keith Wood - July 13, 2020

This rifle offers the features of higher-grade guns without all of the cost.

See More Guns

Magazine Cover

GET THE MAGAZINE Subscribe & Save.

Digital Now Included!

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW THIS MONTH'S ISSUE Arrow

Buy Digital Single Issues

Don't miss an issue.
Buy single digital issue for your phone or tablet.

Buy Single Digital Issue on the Petersen's Hunting App

Other Magazines

Special Interest Magazines

See All Special Interest Magazines

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Phone Icon

Get Digital Access.

All Petersen's Hunting subscribers now have digital access to their magazine content. This means you have the option to read your magazine on most popular phones and tablets.

To get started, click the link below to visit mymagnow.com and learn how to access your digital magazine.

Get Digital Access

Not a Subscriber?
Subscribe Now