Nemo Omen 300 Win Mag – AR Gets A Turbo Charger

There is nothing more American than more horsepower. Not mom, not apple pie, not a bald eagle clutching a baseball whilst curb stomping a commie and humming Yankee Doodle Dandy. While the Euro-weenies ( and our current FBI) are enamored with 9mm, us red-blooded John Wayne disciples developed the 45 ACP, 44 Magnum, and 10mm. While they made lighter sports cars with 2 and 3 liter engines, we created things like the Super Sport and Shelby Cobra. So it is with giddy anticipation this week that I present a gun that sounds like it came off the set of “ The Expendables 7: Everyone Gets Shot in the Face.”

The NEMO Omen has been around for a while, but this is the first time I got my grubby mitts on one. When I heard semi-auto and 300 Winchester Magnum, I assumed the gun had to be gigantic. It is large, but not Micheal Bay oversized. At first glance, you can see the DNA shared with an AR-15. There are a few changes to accommodate the caliber, but it keeps the things I find important.

First off, the caliber choice is uber-manly. 300 Win Mag might not be the best in class for efficiency, but it does bring the pain. You can tell the thought process of the cartridge designers back in 1963. What if we took the 30 caliber bullets Americans are so fond of and made them go ludicrously fast? Good idea Jim! How are we going to do that? Simple. We put a metric ton more powder behind it.

What a 300 Win Mag lacks in ballistic coefficient, it makes up for in anger. Pushing a 190-grain bullet, it will kill anything in North America, and most things in Africa. And for putting Jihadi’s in the ground, accept no substitute. If you want to see a tango cartwheel out of his flip flops, this is the one for you.

So on to the rifle. I have shot a lot of 300 Win Mag out of a bolt action, and I find it to my liking. But for most combat situations, semi-auto is better. Much better. So this is like finding a unicorn for me. The rifle shares all the ergonomic greatness of an SR-25, to include a Magpul PRS stock. The controls are in the same place, with the Omen also sporting an ambi mag release and safety. For the massive round it shoots, the rifle is surprisingly well balanced and light. I tested the Omen Match 3.0, which has a 22-inch barrel. It weighs in at a svelte 11.2 pounds and is perfectly balanced. Small details like a titanium muzzle break and take down pins for example make the difference. Carrying this gun around, it could easily be mistaken for a 308.

The real magic of the NEMO system is the bolt. The Omen was a nexus for the creation of the collapsing bolt system, a patented recoil reducing technology. It sounds like hype, but it really does work. The felt recoil of the Omen was less than most 308 rifles, by a margin. Not only does this give you a longer training day, but it allows you to spot your own impacts at range. That is a massive advantage on the battlefield, where spotters are usually in short supply. To test this, I actually did a mag dump at CQB range. Now granted, I spent 9 dollars. But not only was it fun, I was easily able to keep the gun on target at speed. Not that you would need a double tap with a 300 Win Mag, but you could.

The Omen is a side charger, with a reciprocating bolt handle. That is something I normally dislike in assault rifles, such as the FNH SCAR. But given the role of the Omen, I don’t count it as a negative. The handle is well thought out and secure and stayed put even during the aforementioned stupidity testing.

Reliability wise, the Omen ate everything I threw at it. It features a 4 position gas block, 2 for suppressed, 2 for unsuppressed. Even at the lighter setting of 3, I had no problems with a mountain of Gold Medal Match.

Besides being a side charger, the Omen has an obvious change to the magazine well. Since there is nothing else like it, NEMO had to craft magazines from whole cloth. The outer shell is polymer, with a Nickel Boron coated steel follower. Currently the gun ships with a 14 round magazine, which is P for plenty on most things.

The Omen Match has a barrel cut from a Bartlein blank, though a Proof Carbon Fiber is also offered in the Omen Watchman. Accuracy wise, it performed as you would expect for the price. It easily shot ¾ MOA groups, though, given the single shot that kept it from ½ MOA, it may be capable of more. To be fair, my break in period consisted of eating a sandwich on the way to the range.

The Omen is like nothing else, and it is going to be hard to give back. If our military had any sense, a couple pallets of these would be on the way to our boys in Afghanistan.

MSRP $4900

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About the author: Clay Martin is a former Marine and Green Beret, retiring out of 3rd Special Forces Group. He is a multi-decade and -service sniper, as well as 3-Gun competitor and Master ranked shooter in USPSA Production. In addition to writing about guns, he is the author of “Last Son of The War God,” a novel about shooting people that deserve it. You can also follow him on twitter, @offthe_res or his website,

{ 15 comments… add one }
  • Patrick Gilmore July 20, 2019, 12:44 am

    I just bought a used Nemo Omen and was trying to find out the felt recoil of this beautiful piece of ordinance. I like your article, it’s funny and almost sarcastic in some places. great. thanks

  • Glenn Stedman February 18, 2019, 11:10 pm

    I have the Omen 2.0 Match.
    For loading,190gr Berger’s on top of 71grs IMR4831 and Fed Mag Match 215 primer using Hornady and Winchester new to once fired casing with a velocity at 2900 avg over 10 shot groups and 12fps avg. Don’t see any reason to push it any faster and beat her around.
    Only problem I have is a 3.571 to lands and a 3.491 mag capacity with a weapon that doesn’t seem to like chambering the 190 Berger’s consistently any further than 3.390.
    BUT jambs beyond 3.390 I do believe are due to bullet. Broke it in with cheap off the shelf and pn16331 180gr Noslers stretched to 3.4something with decent loading results.
    Had to send it back not long after receiving to get light strikes FTF issues fixed and told she received a update BCG.
    Tentatively going to change bullets after I burn up the stockpile of Berger’s hoping to get closer to the lands, but……she just hits where you point it regardless of what Berger says about being on the lands, she just drops the round where you point it while allowing you to get right back onto next shot.
    Only bad thing, I use it for hunting and she will catch on every brush while getting the barrel shroud full of snow once you Coban wrap it to stop catching brush. And off the shelf barrel condoms are too small or the brake rips it, so grocery store bigger balloons cut to size is only option.

  • Ray June 26, 2018, 2:45 pm

    Love your review but please add the “tale of the tape”. I want to know the weight, the barrel length, the twist, any other specs without looking them up.

    Also nice still of the muzzle blast!

  • Larry Milam June 25, 2018, 4:52 pm

    I’ve been in love with .300 Win Mag since I bought my Browning BAR 10 years ago. The only thing I’d improve on is the barrel length. Just two more inches of barrel and BAM … you’re there! The advantages out weigh the negatives adding more barrel. It would not be that much more cumbersome or weighty with a little more steel on it.

  • Steve J June 25, 2018, 1:23 pm

    Nice rifle and nice review. I could use one of those.
    But as an “industry pro”, why would you shoot without eye protection? Yes it was getting dark and you had dark glasses, but the dark doesn’t slow down anything headed in your eye’s direction.

  • JoshO June 25, 2018, 11:57 am

    Why the short barrel? You’re going to be sand-blasting that brake withpowder — forget about suppressing the thing. Not to mention losing a ton of velocity. I understand the desire to keep it light but come one…just two more inches of barrel would go a long way. I’d actually want 4 more inches (that’s what she said haha).

  • david n samples June 25, 2018, 10:28 am

    noreen also has an ar in the 300 mag and not as pricey as the nemo. i have one in 30-06 and love it. how about a comparison test

  • Andre Smith June 25, 2018, 10:07 am

    I bought one because I’m sure that the republic of California will eventually ban all semi automatics. A friend in the business is hooking me up with a Nightforce 5.5×22. Can’t wait to shoot it.

  • Triggerpull June 25, 2018, 9:22 am

    Does look like an effective SASS type weapon that can fill in other roles as well. I’ve always been curious how reliable a cartridge that headspaces off the belt would be in an AR–did they do a lot of “fast mag dump” tests with the thing? By far their most interesting development to me is their “shock-absorber” carrier–that by itself adds tactical advantage I would think–I hope they market that without ransoming us to the rest of the ultra-expensive, though very fine, system.

  • G. Moore June 25, 2018, 8:23 am

    Love your writing style. I nearly cartwheeled out of my flip flops a couple times. The Nemo interests me, though I’d like to see a long term durability test before I part with my money.

  • J. Smith June 25, 2018, 6:43 am

    Min barrel length for a magnum is 24″, desirably 26″. 0therwise if a 30 cal with more punch, in a small platform over a .308 is needed or wanted why wouldnt they do this in a .300 WSM or a 30-06. Where a shorter barrel doesnt waste unburnt powder, increase recoil, cost, muzzle blast and decrease the performance to the point the setup defeats the benefits of the magnum round. I liken this to 460 and 500 mags, many used ones can be found for sale, shot once. But, who needs 707 horsepower from a supercharged hemi? I do, and love everytime i punch the gas and watch the fuel gauge drop! Somehow a turbo six cylinder just doesn’t cut it.

    • Dr Motown June 25, 2018, 8:29 am

      Exactly what I was thinking. No velocity or ballistics testing reported. Reminds me of folks who buy 16″ AR10s and don’t realize they’ve turned their .308 into an AK round

      • Dan June 25, 2018, 10:26 am

        Yeah, but this one goes to 11.

  • Stan Karamol June 25, 2018, 5:51 am

    Thanks I was thinking of buy one. You just sold me on it.

  • Joe June 25, 2018, 2:32 am

    How does it compare to the Falkor Petra?

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