Modern Duplex Cartridges by David Tubb (Absolute 2-Hole Ammunition)

About a month ago, I was writing a post about David Tubb’s new rifle and while browsing in his website I came across this very unusual and interesting ammunition. With the subject of experimental ammunition being among my top interests (I am sure of many of our readers’ too), I couldn’t help but write about this. This new ammunition reminds me of the US project SALVO multi-projectile ammunition. It is actually a two projectile load a.k.a “Duplex cartridge”.

So this is a .308 Win ammunition called “Absolute 2-Hole”. It is loaded with two separate projectiles sitting on each other. The combined weight of two bullets is 350 grains. They come with both supersonic and subsonic loads. The two bullets impact in close proximity to each other thus increasing the terminal performance and hit probability.

The first (top) bullet is a flat base hollow point and weighs 135 grains. It has a thin jacket with pure lead core and is supposed to expand quickly. The second (bottom) one is a round nose soft point bullet and weighs 200 grains. The second projectile’s purpose is to provide better penetration. So unlike SALVO projectiles, these are purposely made to perform differently on the target.

The Absolute 2-Hole ammunition is designed to be possible to shoot from AR-10 style semi-auto rifles without a need for any modifications. Projectile lengths and weights are calculated so that they are compatible with barrels that have 1:12″ or faster twist rates. And of course, it will perfectly work in bolt action (or any other manual action) rifles too.

Here is a video showing the performance of these duplex loads on steel targets:

The Absolute 2-Hole ammunition comes in 20 round boxes with MSRP of $59.99.

Besides being a very interesting round in terms of ammunition technology, this loads can have some unmatched practical advantages too. At least it can definitely be a good hunting round.



Hrachya H

I was born and currently live in Armenia, where I work in a family business of leather goods manufacturing. Being a retired sergeant of my country’s armed forces and a lifelong firearms enthusiast, I always enjoy studying firearms design, technology and history. Also my knowledge of Russian allows me to translate and make Russian/Soviet/Combloc small arms related information available for the English speaking audience.
Should you need to contact me, feel free to shoot me a message at TFBHrachyaH@gmail.com


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  • Steve

    I’ve always wondered this about duplex loads:

    NFA defines a machine gun as any firearm that shoots more than one ‘shot’ per trigger pull. Unfortunately, ‘shot’ doesn’t specify if it means bullet or cartridge…

    Any foreseeable issues, here? I suppose with the ATF, we might as well flip a coin.

    • Steve

      I guess if there’s no issue with shot shells, this shouldn’t be a problem…

    • SGT Fish

      It doesn’t even mean two cartridges. One shot can be multiple cartridges from different barrels. Such as the Gilboa double barrel ar15. Or that double barrel 1911. Or those new double barrel pump shotguns.

    • Flounder

      I am possitive that the ATF has defined “shot”. My guess is that they defined it as a complete cartridge. Otherwise every shotshell of any type would be a machine gun. Even those .22lr shotshells.

      • Gary Kirk

        BREAKING: Remington is now the world’s largest manufacturer of model 870 machine guns…

    • roguetechie

      Since they’ve approved stuff like the side by side double .45’s I don’t think so, but ATF consistently refuses to make clear and cogent guidelines that lay out the same rules for everyone who applies preferring to leave every decision up to the whim and fancy of whichever FTB examiner a design’s sample article lands on!!

    • kyphe

      The actual definition in practice is one pull of the trigger = one fall of the hammer/hammers(concurrent not sequential)= one firing sequence detonation/detonations(concurrent not sequential) number of projectiles is not an issue. You are not allowed to have a roman candle like bullet which fires a sequence of shot not are you allowed multiple barrels firing in sequence either from a single or multiple hammer falls. You are allowed to fire multiple projectiles from a single or multiple barrels in a single volley or salvo.

    • Ralph Napier
  • Giolli Joker

    I found out about them as well while reading around the new Tubb rifle (after seeing the article on TFB).
    I can see the purpose and the advantage in subsonic form, not so sure about the supersonic version.

  • valorius

    Only $3 a shot huh?

    • Flounder

      It’s 2.50$ so a total steal. Its less than paying for 2 cartridges right?

      • valorius

        I suppose to someone making big $, $20 a cartridge would be cheap.

        • roguetechie

          Depending on what you’re hunting and or what type of animals you could find yourself needing to stop quickly before it mauls and kills you… I could see this being a reasonable expenditure.

          Plus you gotta factor in paying the early adopter tax, and the ammunition hipster tax.

          On another note, Nathaniel’s post showing high quality images of the Winchester SPIW entry awhile ago already had me considering an ultimate retro what if build of the Winchester SPIW and it’s drum in 5.56 / an experimental round design heavily influenced by 5.56 FABRL / 5.45 as the preferred chambering options with a 7.62 & or an upsized version of the experimental 5.56 cartridge above.

          Now with this ammunition coming to my attention I really want to do it!

          • valorius

            If i made twice what i do, i’d buy all kinds of stuff that i think is overpriced now, probably.

          • roguetechie

            Even if you were forced to dump 5 rounds into a charging bear or moose it’s still $5-$10 less than the copay for a doctor visit on many medical insurance plans…

            Combine this with the fact even if the bear only got one good bite or rake of his claws and or the moose only stomped on you once you’re looking at an ER trip which will cost you substantially more than the standard office visit copay.

          • Tassiebush

            I think of it in a context destructive vermin. Most can cause significantly more per animal than the cost per round.

          • roguetechie

            Right, using the proper tool for the job can save time, aggravation, or even your life!!

          • Tassiebush

            Penny wise pound foolish, A stitch in time saves nine etc definitely applies.

          • roguetechie

            Exactly… All the “money you saved” by using the wrong tool achieving mediocre and ugly results while turning a half hour job into a 6 hour death match where, like hockey, if you’re not bleeding you’re not doing it right is all too common these days.

            This isn’t to say that you need to go out and buy top tier professional grade single use tools to accomplish every project either!

            However, in many cases googling for nice high resolution images of a specialty tool from several angles and retiring to the garage to make something which replicates it’s function and etc as either a standalone version or designed to work with something like a socket wrench you already own is perfectly acceptable.

            Even if you spend 6 hours researching and making the tool and finish the job in half an hour it’s still very much a victory because you have done the job right and can do it again in the future and only spend half an hour doing it each subsequent time.

            Plus if it’s something like a proprietary fastener head for a coffee machine or etc you can always anonymously post dimensioned drawings etc to thingiverse or drop a line to the staff at hackaday who will help you set up a traveling loaner tool ring that passes it from one person who needs it to the next!

            Doing either of these things and or a few others “pays for the 6 hours of labor you put in making the tool”

            And as an added bonus you have likely learned at least 3 new things in the process of researching and designing your tool.

            Plus things like sharing the service manuals of cars that the manufacturer has copyrighted and sharing data on how to make tools that let you work on your coffee machine yourself are very much acts of civil disobedience in the vein of the Boston Tea Party and etc so…. Yeah…

            Viva LA revolution!

            Or something to that effect

          • Tassiebush

            There’s a genuine freedom in mastering the technology we have and breaking our dependence on others to provide things.

          • roguetechie

            The only true freedom comes from not being forced or cajoled into becoming dependent upon a state

          • Tassiebush

            Agreed and I’d add independence from a few more entities to that statement. Companies, body corporates, gangs, faiths etc. It’s okay to have most of those (not so much gangs) but it’s clearly good to be able to opt out of their influence.

          • roguetechie

            Could not agree more, however I was trying something new and editing my replies for brevity rather than write the great American novel in response to every 6 word reply I receive LOL

          • Bierstadt54

            Indeed. That being said, one would have to be convinced this duplex load really is the right tool for the job – all it really has going for it is the David Tubb name, to my way of thinking. I’ll take one good, properly designed high-speed bullet over 2 much slower ones.

          • Tassiebush

            Yes agreed. It’s effectiveness isn’t by any means established in comparison to regular good quality ammunition.

          • valorius

            Are they marketing this as dangerous game ammo?

          • roguetechie

            Idk Valorius I’ll be honest with you here in that I was thinking of using this in a 308 gun as last ditch OH SH** BEAR!!!! ammo

          • valorius

            It would probably work for that.

          • roguetechie

            If I were them I’d advertise it as defense ammunition against bears etc Tubb duplex if you have to say something to an angry bear

            SAY IT TWICE

          • valorius

            This stuff would be really neat in something like .45-70.

          • Tassiebush

            Income is part of it and I guess another fiscal consideration is putting ammo cost into perspective compared to other shooting trip costs. Total cost still matters of course so ammo cost may be a major factor but it can be significantly less than other components of the trip.

          • iksnilol

            308 for dangerous animals?

            That’s a good joke if you’ve got a dark sense of humor.

          • roguetechie

            In the Continental United States it could actually serve pretty well all but a few places, and even in those places you’re far more likely to see some sort of 308 truck gun than a belted magnum 375 Holland and Holland LOL

        • Flounder

          ahem, sarcasm man… It’s stupid expensive but you DID embellish a bit. I just had to set you straight. Very important to get that 1/6 price correction.

          • valorius

            I’m actually serious- for some people $3 a round is nothing, i guess. I got your point though. 😉

    • iksnilol

      To be fair, the bullet is twice as heavy as regular 308 loads.

  • Sid Collins

    Why did the two bullets impact left and right of each other rather than up and down?

    • SGT Fish

      Possibly windage having a different effect on the two different shapes and weights of the bullets. I think them hitting vertical would be better though. Better chance of hitting at a distance

      • Sid Collins

        The claim is that it was only at 50 yards. There is an explanation due to the users or prospective customers.

    • Wade Kirby

      If the range is long enough I’d say the lighter bullet slowed down faster than the rear bullet and got kicked in the tail causing them both to wobble. (Or they are just wobbly to start with.)

  • Reality

    If they seperate the BC goes to s*it in milliseconds.

    It doubles frontal area, + takes away the aerodynamic of a boat tail from the tip, and takes away the aerodynamic of a nose ogive from the base.

    A single projectile with a good construction (EPR / OTM / HP / TSX / SP / PTHP) will have better terminal ballistics simply due to energy retention.

    And salvo doesnt work well at all with only 2projectiles. 3 are minimum, 4 to 5 are usefull, but the general problem of salvo is you cant control the pattern well.

    • roguetechie

      Even with up to 5 projectiles it doesn’t work all that well unless you take it salvo squeeze bore.

      • Reality

        Thats what i meant. Otherwise pressure is too high. /or multiflechtte sabot which work best with salvo anyways.

  • DADPOOL

    so, aren’t duplex loads where you mix black and smokeless powder or two different smokeless powders or am I mixing up my firearms obscuria..then everyone chimes in and tells you not to do it.

    • roguetechie

      Duplex loads = 2 bullets 1 case

      • DADPOOL

        do a little googling and report back then. it’s an old idea that goes back a long time. seems to me the commenters and even the op are using the term incorrectly.

        • roguetechie

          I’m using the term as everything from project salvo onwards has used it…

          I’ve only got 4 or 5 dozen pdf’s of patent applications, industry proposals to different branches, ARL, and other documents from the 60’s until now that use duplex etc to describe multiple projectiles in a single cartridge case.

          So no, I am not using it wrong

          If you have issues with this please take it up with DOD not me

          • DADPOOL

            its just the term(for mixing powders) has been around since the advent of smokeless powder. it seems we’re kind of a little both right and other use the term as well as you have.

          • roguetechie

            I’ve not once ever heard the term duplex used to describe blending multiple powders, and since duplex rounds have been around since the 50’s…

            Yeah

          • FWIW: I’ve seen “Duplex” and Triplex” used in terms of layering propellant charges inside the cartridge case. The original .454 Casull loads of the 1950s were layers of Bullseye, Unique, and #2400. The propellant charge was compressed to keep the layers from mixing.

            Back in the 1930s/1940s, Elmer Keith and C.M. O’Neil used the term “Duplex Load” to reference their long primer tube/forward ignition schemes.

            Oh, and multiplex projectile loads for rifle and handgun cartridges go back much further than the 1950s. Georg Luger even had a patent for the concept.

          • roguetechie

            Very interesting, thanks Daniel…

            This is why i made it very clear that i was just referring to what i have personally seen WRT the subject

  • Flounder

    This is an interesting idea that I think is doomed to fail miserably. Although I am interested in how the subsonic loading will turn out and if they will find a way to get this into a 300 blk cartridge. At 350grs my guess is that the 308 is already pretty strained for internal volume and a much small case wouldn’t be able to hold the bullets and the powder.

  • Brett

    Anyone else giggle at the title? ……Anyone?

    • Gary Kirk

      Wondering if it was made for the DP-12 were you???

      • Brett

        I mean, it is a surefire way to get a STD-15.

        • Gary Kirk

          Don’t forget the std-1911.. Remember the DP led to two STDs..

    • Giolli Joker

      I tend to read the name of this cartridge as abs-hole…

  • Goody

    A 335gr 308 load, F class eat your heart out…

    Though I think when they specify ‘supersonic’ they could easily qualify that as ‘barely’.

  • Seth Hill

    What about a round that is similar to this, but they don’t separate in flight. I’m thinking that the lighter “nose” piece be scored inside and when the round hits the target, the second piece’s momentum would drive through the first, causing the first to open up and start to mushroom. The second piece would continue into the target and yaw, cavitate, etc causing damage.