MPA300 Guardian .300 Win. Mag. AR-15

The MPA300 Guardian is my pick for best rifle at Media Day (the range day that proceeds SHOT Show). The elegant looking is approximately the same size and weight of the Army’s .308 Win. M110 Semi-Automatic Sniper System but being chambered in .300 Win. Magnum it has up to twice the range and packs a much greater punch.

mpa300 rifle-1

mpa300 rifle-2

Sitting down to shoot the MPA300, and having shot many hunting and tactical bolt action rifles in my time, I braced myself for the recoil. I was very pleasantly surprised. The recoil is light. The Stoner gas system soaks up much of the recoil not canceled out by the muzzle brake.

mpa300 rifle-3 mpa300 rifle-4

The MPA300 utilizes as many standard AR-15 or AR-10 parts as possible. The receiver is about an 1″ (maybe slightly more) longer than an AR-10 rifle to accommodate the larger magazine well but otherwise looks and feels the same. The stock is a Magpul PRS (7.62) and the handguard is a Precision Reflex 208 AR Delta. The barrel is 20″ long that MPA machine from a Kreiger barrel.  The chambers are cut by hand for the best possible bore alignment. It has a rifle-length gas system.

The MSRP is $5,399.

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Jeff

    Why handicap it with a 20 inch barrel?

  • Esh325

    For military use, I wonder is it as reliable and durable as the bolt actions currently being fielded in .300 winchester magnum?

    • Aaron E

      Esh325 I got to shoot it as well, and the rep said that they are building these rifles to be accurate to 1500 yards. According to their website each rifle is guaranteed to be sub-MOA, with some rifles attaining 1/2 or 1/3 MOA. I was able to hit a steel target at 565 yards on my second shot, barely missing the first because of some wicked cross winds.

    • I can say that it ran all day, to about 2600rds without cleaning before the first failure. The barrel went from 1/2MOA to about 1MOA, just from shooting today. It was very reliable.

  • hkryan

    That rifle looks very well thought out!

  • Jack Morris

    Hmm, a “budget” Nemo Omen.
    Looks like Nemo wasnt the only company working towards a semiauto sniper bid from the miltary.

    • rdsii64

      This rifle is way better than a Nemo Omen.

      • Jack Morris

        Budget doesn’t always mean lower quality, just lower price.
        What makes the MPA300 “way better” than the Nemo?
        Not trying to be snarky by any means, I’m genuinely curious what the substantial differences could be.

      • Jeremy Miller

        I have not shot this rifle I have shot a nemo and have to say If this is using a standard style Ar15 -10 Bolt I don’t see how it could out preform the nemo. A nemo has a buffer between bolt head and carrier as well as on back of carrier as well as the normal Buffer and then a amazing muzzle break. And then three of the four models also have a adjustable gas system as well so you can dial it in if shooting lite loads verses heavy. I work for a gun dealer in oklahoma and have shot the nemo I will say this looks Like a nice gun and A would love to shoot one to compare. The nemo I shot was the partka with out the adjustable gas and It had less felt recoil than a aK47 shooting a 190 grain bullet. We sell that model with nice drag bag and six mags under $4K. They also have standard a Geissele SSA-E 2-stage Trigger.

  • Lance

    Now that’s a cool new toy. I think Army could look at this.

  • Juice

    Thanks for reminding me of my A-TACS fetish.

  • OliverTabuger

    I was like yes, Yes, YES, YES!!!!

    Then I saw the price. No. 🙁

    • Cliff Mainor

      exactly my response!

  • Seth Hill

    Shouldn’t the title be “MPA300 Guardian .300 Win. Mag. AR”, as it is not an AR-15 or even an AR-10?

  • DustCovered6

    Any word on barrel life, and if they’re going to offer something in .338?

  • WarDaem0n

    I know Brandon (the owner/founder of MPA) and yes you can get these chambered in pretty much any cal that the mag well is big enough to handle, including .338 lapua, .408, .416, .458 Lott, etc.