Alexander Arms’ Expanding 300 Blackout Subsonic Ammunition and Ulfberht Upgrades

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The 300 Blackout caliber has become the second most popular caliber for the AR-15, after the 5.56mm/.223 Remington caliber. What the 300 Blackout caliber especially excels in is firing subsonic ammunition to use in conjunction with a suppressor. However, subsonic 300 Blackout ammo is expensive and due to it’s slow subsonic velocity, most loads have rather unimpressive terminal ballistic performance. The most popular projectile used in subsonic 300 Blackout ammo is the 220 gr Sierra Matchking OTM. While it’s a good bullet but it costs 55 cents each in bulk and it doesn’t expand.

For this reason, Alexander Arms had spend the last 2+ years to develop their own projectile for the subsonic 300 Blackout, which is significantly cheaper than the Sierra Matchking and it expands like a pistol hollow-point.

 

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A picture of the very early mock-ups of the Alexander Arms 300 Blackout from over 1.5 year ago. The projectiles in the images are clearly machined copper slugs and those are probably only used for testing magazine feed purpose.

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Alexander Arms 300 Blackout Subsonic Hollow point Ammo

 

The production projectile with the conventional metal jacket construction. The Alexander Arms 300 Blackout Subsonic ammo will be available in both the hollow-point and FMJ versions. The projectile weight is 180 grain for both versions. Of course, the expanding hollow-point version is the more interesting of two. The MSRP for a box of 20 is $18.50 for the FMJ and $19 for the hollow-point. The cartridge case is likely new manufactured brass case from Hornady with the custom Alexander Arms head-stamp.

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The FMJ version of the Alexander Arms 300 Blackout Subsonic Ammo. The bullet tip is closed.

Interestingly, Alexander Arms will be loading their subsonic 300 Blackout in two barrel length versions: one version for 10.5 inch short barrel, and the other for 16 inch standard barrel. Both will have the muzzle velocity of 1000 fps.

 

In this video, Bill Alexander explains why he developed the new subsonic projectile:

 

 

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Also new from Alexander Arms is the new lightweight Ulfberht barrels. You can read about my first impression of the semi-automatic .338 Lapua Magnum rifle here.

 

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Close up of the new Ulfberht barrels from Alexander Arms: the carbon fiber wrapped version made by Proof Research, the coin dimpled version and the traditional heavy fluted version.

 

Also new from Alexander Arms is the update version of the Ulfberht rifle that uses the above lightweight barrel, plus carbon fiber and titanium parts to reduce the weight by 15%. It also has a re-tuned gas system that making it even softer shooting than the original Ulfberht. Those are the M-Lok slots on the carbon fiber handguard.

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Writer and gear editor with articles published in major gun publications. A five year combat veteran of the US Marine Corps, Tim is also part of Point & Shoot Media Works, a producer of photography, video and web media for the firearms and shooting sport industry. Tim’s direct contact: Tyan.TFB -at- gmail.com


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  • BattleshipGrey

    I haven’t really gotten into all the hype with .300blk, but perhaps if my state wasn’t NFA stupid I’d give it another look. I’m glad to hear that some more promising subsonic rounds are pending though.

    • Kyle

      Honestly the short barrel whizzbang suppressor stuff doesn’t mean much to me. However it does seem like a much better round for AR hunting for things bigger game. Plus I actually do love that all you need it a new upper and everything else can stay the same.

      • nate

        You dont need a new upper, you just need a new barrel.

        • kregano

          Technically true, but for most people, barrel swaps on an AR are a massive hassle. It’s just easier to grab a .300 Blackout upper and swap the BCG & charging handle from a 5.56mm upper.

          • Evaris

            And at such point I am of the opinion that you’re better off grabbing a 6.5 Grendel, or a 6.8 SPC, or a .458 SOCOM, or a .50 Beo upper or something for hunting. Or 7.62×39 for that matter. .300 BLK is meant to be suppressed, if you’re feeding it supersonic ammo it just seems… like there are better options out there, to me. I mean 7.62×39 is cheaper and has pretty much the same ballistics and hunting capacity when it’s supersonic vs supersonic.

            Or am I missing something about .300 BLK?

          • Sianmink

            It’s a royal PITA to get 7.62×39 to feed reliably in a magazine that will fit in an AR lower, because of the required straight section.

          • Jeffrey

            I have about 2000 rounds of TulAmmo 154 grain SPs through my SOTA Arms 7.62×39 not a burp.

          • Toxie

            Plus there are way better bullet selections for 300 blk if you reload, and 300blk is far better from a reloading perspective anyways. Add in that you get full velocity out of a sbr, its a good round.
            And that’s not even addressing the subsonics, which x39 doesn’t have the capability to do!
            To be fair though, you do need to reload to take advantage of 300blk to the fullest.

          • Evaris

            Okay, ammo capacity aside, assuming a hunting rifle, is there a reason to choose Supersonic .300blk over 6.5 Grendel or 6.8 SPC if you’re reloading, or when Subsonic, over .458 SOCOM or .50 Beowulf?

          • The primary benefits of .300 BLK are a) that it works with heavy subsonics and b) that it’s supersonic loads work much better out of short barrels (9″) than 5.56. It’s ideal for SBR/Pistols and supressors.

            Using a 16″ unsuppressed would likely negate any advantage over 5.56 or other calibers.

    • Griz

      The 300 blk was going to be a range toy for me, but after watching my daughter take 2 deer with it this year I’ve switched to .300 black myself. The bullet’s energy stays in the deer and not out the otherside like my .270 I don’t care much for NFA tax/ATF nosing around, so 16 inch works for me.

  • AndyT

    That’s still expensive, especially for FMJ. I can load leatherheads 220 or 240 gr subsonics for less then the cost of new production .223 production ammo (which I typically pay .30 a round for).

    I’m curious to see if they will sell just the expanding projectiles as components for those of us that roll our own.

  • Riot

    Whats the missing section on the LHS of the forend for?

    • Kevin Collins

      The slot is for easy removal of the gas cylinder when cleaning or maintenance is required.

  • Chase Buchanan

    I’m not especially familiar with .300 Blackout, but these look awfully long. Will they fit in an AR-15 magazine?

    • Vitor Roma

      Yes, with the same capacity, and uses the same bolt also. Only thing that needs to change is the barrel.

      • Chase Buchanan

        I mean, I know that’s what .300 Blackout was created for, but I wasn’t sure if these particular examples would. I know that there are super-long 5.56mm loads, for example, that won’t fit in an AR magazine and have to be loaded by hand one at a time through the ejection port.

        • Having the long bodied and round nosed ammo (Hornady 220gr shown in picture) helps in feeding while being able to use a heavier bullet without decreasing case capacity. No need to just use 1680 with 240 SMK loads.

  • gunsandrockets

    Video interview well worth the time to watch.

    • nova3930

      Yep. Bill Alexander knows his stuff when it comes to firearms design. He’s totally right in that big honkin 300BO subsonic bullets really just need to be big pistol bullets….

      • Secundius

        @ nova3930.

        Actually Nothing New About It. During WW2, the SS developed a Nahpatrone (Near Cartridge) 7.92×57 in conjunction with the HUB-23 Silencer a 75% reduction in “Noise”. Barely Audible to the “Human Ear”, with a Muzzle Velocity of ~721-ft/sec and a Range of ~300-meters…

  • Giolli Joker

    The Ulfberht with Proof barrel becomes a sexy thing…

  • wildbillb

    i thought 7.62 x 39 fixed this price issue…

    • Laserbait

      Where are you seeing 7.62×39 subsonic ammo for for $0.50 a round?

    • 7.62×39 is cheap for surplus blaster grade ammo. For hunting, precision, subsonic, etc. There are few choices, marginal quality and high cost. If you want to buy or load match ammo, you are lucky to find five choices for it. On the other hand, 300 BO provides about a hundred times as many viable choices of projectile in every quality bracket and application because it uses a .308 bullet rather than a .312.

      Moreover, for a person using cast bullets subsonic, milspec level accurate ammo can be made for 5-7 cents a shot.

      Match ammo for 30-60 cents depending on projectile. Accurate match ammo for 7.62×39 is scarce and tends to be over a dollar a shot.

      Not only that, but molds and data are being developed to optimize harder cast bullets for supersonic performance. With the right alloy and recipe, you get full supersonic performance in the 1.5-2moa range for about 9 cents a shot. The brass is easy to come by in a way that is not true for 7.62×39. It’s just a more versatile adaptable starting point.

      This really is a crowdsource developed cartridge and it has been improving rapidly over the last couple of years.

  • DIR911911 .

    would love to see what that bullet does in a big block of gel

  • Michael R. Zupcak

    Anyone with a super-short (under 8″) .300 BLK here?
    Can super-short .300 BLK pistols/SBR’s cycle subsonic ammo WITHOUT a suppressor?

    Seems like it would be a better choice for AR pistols in states that don’t allow suppressors because it’s designed to burn the powder in a shorter barrel. But if it doesn’t cycle BOTH kinds of ammo w/o a suppressor, it doesn’t seem like a good idea.

    • 1. Yes
      2. Yes
      “But if it doesn’t cycle BOTH kinds of ammo w/o a suppressor, it doesn’t seem like a good idea”

      Actually, it doesn’t matter since you won’t be shooting subsonic ammunition in a un-suppressed weapon. Subsonic’s aren’t silent without their suppressor. If you don’t own a suppressor it will be irrelevant to use subsonic ammo, hence no need for subsonic’s to cycle without a suppressor.
      If you do for whatever reason you have two options.
      1. Get a barrel with a larger gas port
      2. Get a Bulgarian style 4-piece flash hider (adds backpressure, retarding barrel depressurization).

  • GunFarce

    Maybe I missed something?

    ” The most popular projectile used in subsonic 300 Blackout ammo is the 220 gr Sierra Matchking OTM. While it’s a good bullet but it costs
    55 cents each in bulk and it doesn’t expand.

    For this reason, Alexander Arms had spend the last 2+ years to
    develop their own projectile for the subsonic 300 Blackout, which is
    significantly cheaper than the Sierra Matchking and it expands like a
    pistol hollow-point.”

    Then Below

    ” The Alexander Arms 300 Blackout Subsonic ammo will be available in both
    the hollow-point and FMJ versions. The projectile weight is 180 grain
    for both versions. Of course, the expanding hollow-point version is the
    more interesting of two. The MSRP for a box of 20 is $18.50 for the FMJ
    and $19 for the hollow-point.”

    That’s 95 cents a round? How is that “significantly cheaper” than 55 cents a round?

    • LilWolfy

      The projectiles alone are 55 cents per with the 220gr SMK. A complete cartridge loaded with it is even more expensive due to the cost of the brass.

  • Timothy G. Yan

    Does the Remington expanding? It’s absolutely garbage bottom of the barrel. ammo. I have Tula steel case ammo that shot better.

    • I was comparing it to the AA FMJ’s. Still, not a great value.

  • Anyone know if they would be selling these projectiles as a component?

  • Cotter Sayre

    So how is the .300 Blackout better than a simple low-cost basic +P .45ACP?

    Signed,

    -Confused

    • AlDeLarge

      It uses all the same parts as a 5.56 AR, except the barrel. Upper, lower, bolt, magazines, all the same. It’s also designed for use in a ~10″ barrel, unlike the 5.56 which is made for 20″. The 300 BO is great for SBRs and AR pistols that way.

      But the subsonic rounds are very similar to .45 ACP energy/momentum at short ranges and .357 MAG for the supersonic. You do get better effective range with the rifle bullet though.

      • Cotter Sayre

        Thanks, now I see its utility.