PolyCase Ammunition’s New .357 Magnum ARX

PolyCase 357

PolyCase Ammunition announced the release of their latest round in the Interceptor Preferred Defense line of ammo: the ARX in .357 Magnum.

The traditional powerhouse load is known for its recoil and muzzle blast in addition to its near legendary status as a man stopper. PolyCase uses its ARX bullet in the new load, which is light for the caliber: 86 grains. Historically, self-defense .357 Magnum loads use bullet weights ranging from 110 grains to 158 grains. As heavier bullets tend, but not always, to generate more felt recoil, the lighter ARX bullet suggests that the load may be easier on the hand than other loads.

A light bullet can often be driven at much faster speeds than a heavier one, and PolyCase added a little mustard on this fastball. The advertised muzzle velocity is 1,650 fps. Many of the 125 grain Magnum loads are advertised around 1,450 fps. With the lighter mass and increased speed, the approximate muzzle energy is 520 ft-lbs.

Frankly, I don’t know how the increased velocity will impact the performance of the ARX bullet. If you are not already familiar, the bullet is a polymer-copper projectile that is shaped in a way that it appears to “screw” into the target. The bullets are not designed to expand or fragment, yet are designed to not over penetrate either. It is an intriguing concept, though one that I am not willing to bet my life on at this time.

Richard Johnson

An advocate of gun proliferation zones, Richard is a long time shooter, former cop and internet entrepreneur. Among the many places he calls home is http://www.gunsholstersandgear.com/.


  • BattleshipGrey

    Interesting. I don’t think I’d want to rely on these either. I always prefer 125 grain pills for .357 mag. That seems to be a hard option to find in bulk though.

  • Ronin John

    is the ammo called Inceptor or Interceptor?

    • Steve Truffer


  • Comrade Misfit

    Hasn’t there already been a lot of research into the issue of whether or not any handgun can hit with enough velocity to make use of the “temporary stretch cavity” mode of wounding?

    • PK

      Some, less than you’d think. Answer – yes, sometimes. More research is needed, frankly, and eventually I’d love to see a handgun firing a small caliber, very dense bullet at 2,500+ FPS… it’s barely possible to do such a thing safely in terms of chamber pressure and wear on the parts, but we’re getting there.

      My ideal handgun would fire a 40-80gr bullet of small diameter (4-7mm, say) at a minimum of 2,500FPS. It’s doable, technically speaking, but harder to do in a semi-auto and harder still in an acceptable size and while expecting any real lifespan of the gun itself.

      • Giolli Joker

        6.5 CBJ?

      • .22 Reed Express is the closest out there.

        It’s a 7.62×25 necked down to .224, and launches 33gr bullets at 2500fps, and 40gr at 2200fps.

      • gunsandrockets

        I think the PLR-16 does 2,400 fps MV with M193 ball. IIRC tests show the bullet deforming rather than fragmenting and performing rather like a soft-point bullet.

        Aside from velocity, I suspect there is a basic floor of energy needed to generate the dramatic temporary stretch cavity damage which leaves permanent damage. Perhaps 1000 fpe?

    • AC97

      If I recall correctly, the threshold is like 2,000 feet per second for the temporary stretch cavity to actually do anything of significance in flesh (remember, flesh is more elastic than gelatin), so that means things like the Extreme Defender and this ARX are basically just glorified FMJs at pistol velocities.

      • Vitor Roma

        The Xtreme Defender are much slower than 2k feet per second. There are inumerous tests showing that the XD performers equal to a very high end hollow point.

        • AC97

          Because gel is less elastic than flesh; just because something looks cool in gel, that doesn’t mean an actual wound will look like that, by any means whatsoever.

          Once again: pistol velocities don’t cause a temporary stretch cavity to do much damage at all because flesh resists tearing to a greater extent than gel does.

          And even if all of that weren’t true, you shouldn’t carry XD ammo because of overpenetration.

          • Vitor Roma

            Gel is not flesh, muscle and bone; we all know that. But gel serves to indicate if the bullet is good at transfering energy. And all the tests done with XD bullets has shown it behaving nothing like a fmj.

            Iraqveteran8888 tested the .45 and MAC tested the 9mm againt all kind of barriers. So, how the a bullet that does 18 or less inches of penetration is a “fancy fmj” when all tests shows the opposite?

          • AC97

            You really aren’t understanding this, are you?

            I’ll try to sum it up here: It may make a bigger temporary stretch cavity due to its design than an FMJ, but due to the fact that it’s not going fast enough for it to actually matter given that flesh has a greater ability to return to its original shape than gel, it’s a glorified FMJ, because the thing with pistols is that damage is mainly caused by the bullet crushing tissue (the permanent stretch cavity), and since the XD doesn’t expand, thereby crushing less tissue, a hollow-point causes more damage than the XD in actual tissue, because it crushes more tissue.

          • guest


            At the absolute least I will wait for someone to shoot a few game animals with these bullets, and then we will see how well the concept works in real living tissue.

            I am willing to be convinced that it could be a real improvement, a real step forward, but I want to see empirical testing. And especially with handgun bullets, empirical testing doesn’t end with blocks of ballistic gelatin, it just begins there.

          • Vitor Roma

            It is not the expansion per se that causes more damage, it is the energy transfer. Expanding into a much larger non-aerodynamical shape is a very obvious and efficient way of transfering kinectic energy. Lehigh found a different way to do that. 500 joules inside 16 inches is 500 joules inside 16 inches. The problem with fmj is not not expanding per se, but not being able to transfer the energy in a short space.

          • AC97

            Have you shot meat with this round? Other people have, and they’ve found that it doesn’t leave a bigger hole than an FMJ, because guess what? It’s not going fast enough, and tissue resists tearing much more than ballistic gelatin.

    • Evaris

      With regular FMJ’s, yes. It should be noted that these bullets are, however, designed to focus hydraulic force at a 90 degree angle, so they may infant create substantial wounding.

      I know that the Lehigh Defense bullets of similar design seem to leave wide wounds in ballistic gel and pork tests, so I’m quite willing to believe that polycase loads will as well.

      • Comrade Misfit

        I’ll wait until there has been some real-world experience.

      • Marvin

        “so they may infant create substantial wounding.”

  • snipehunta

    Those billistics are similar to the 7.62×25.

    • Tim

      Very observant, Snipa, I noticed that right off as well.

  • Vitor Roma

    The 140 grain arx for the .458 socom is devastating, more than most 300 grain around.

    • maodeedee

      What may be “devastating” in a block of jello doesn’t always translate to devastating in the real world.

  • Dr. Longfellow Buchenrad

    So the company is called polycase, but the case is brass and the bullet is polymer?

    I would much prefer to keep the weight in the bullet and remove it from the case instead.

    • yodamiles

      Actually, the company used to make polymer case pistol ammo in wide variety of colors. I don’t know why they stopped and pretty much erased all info regarding the case.

      • PK

        The polymer cases from a few companies failed repeatedly and quite spectacularly, in a few systems… you should have seen what a HK’s fluted chamber did with PCP’s .308 ammo.

        That aside, it makes sense in lower pressure (compared to rifles) chamberings, and PolyCase’s website seems to indicate they still do at least intend to offer polymer cased ammo in the future. It’s on their “About the Company” page.

  • 86 Grains? LOL! No.

  • PK

    Both that and Brno’s FK 7.5mm are getting there… I like the 22 TCM, and I’m waiting eagerly for the 7.5FK pistols to be imported!

    • Marvin

      I too want to play with the 7.5FK cartridge in autoloading pistols, not necessarily that BRNO one.

    • El Duderino

      You could build a pretty fantastic double stack 1911 in 9×25 Dillon for $5000. Shoot 115gr 9mms at 1800 fps all day long. Not quite what you’re looking for, but darn close.

      • PK

        You’re right, but as you also said, it’s not really what I’m looking for.

  • Hoplopfheil

    I picked up a box of Ruger ARX in .38 Special (same as Polycase Inceptor), and thought “finally I’ll get some real muzzle energy out of a .38!”

    Then I did the math, and was reminded how wimpy the .38 Special is.

    • DrewN

      Buffalo Bore Heavy .38 Special. 158 grain soft lead semi wadcutter hollow cavity. 1162 fps (474 ft. lbs.) — S&W Mt. Gun, 4 inch

      • Hoplopfheil

        That sounds like it’d blow my Taurus into pieces.

        • maodeedee

          Then what you need is the Buffalo Bore Standard Pressure Short Barrel Low Flash Heavy .38 Special Ammo – 150 gr. Hard Cast Wad Cutter (you need to Google it, I can’t post link for some reason)
          I carry these in an old model 38 airweight humpback.

          868 fps (251 ft. lbs.) — S&W mod. 60, 2 inch barrel
          890 fps (264 ft. lbs.) — S&W mod. 66, 2.5 inch barrel
          961 fps (308 ft. lbs.) — Ruger SP101, 3 inch barrel
          1005 fps (336 ft. lbs.) — S&W Mt. Gun, 4 inch barrel

  • Disarmed in CA

    How fast out of a 2″?

    • maodeedee

      Not fast enough with such a light bullet. The 86 grain “Phillips Head” projectile hardly weighs any more than a 36 caliber round ball.
      This is not any kind of technological advancement, it’s just gimmickry in my opinion.

  • gunsandrockets

    Designed not to fragment? IIRC even the 9mm polycase tends to break up. This .357 will probably fragment even worse.

  • gunsandrockets

    Seems like an awfully light load for such a light bullet.

    However, despite whatever drawbacks this offering may have, I applaud the introduction of new and innovative cartridge concepts.

  • Marvin

    Shoot a razorback in the forehead with this on video. Show this works. How does Sectional Density translate from polymer and copper compared to cup and core projectiles with in a given bullet weight and diameter>? There are rules to this game that have been established. Selling velocity and whoa dude factor may sell widgets, but these widgets may have a detrimental inefficiency that may get some whoa bruh, dude killed.

  • missourisam

    I am not a fan of any .357 round but the 125 gr. hollow point at max velocity. Our issue ammo was a 110 gr. hollow point at hyper velocity. It was supposed to be the greatest thing since toilet paper. In practice it was really what toilet paper was designed to remove. The tiny hollow filled with clothing fiber and was the same as a round nose bullet, and high velocity zipped through so fast and easy that the person being shot didn’t realize they were hit until they started bleeding out internally. In the mean time they were still shooting.

    No thanks, I’ll stick with a 125 with a huge hollow at over 1450 FPS, or preferably a 185 gr. .45 at over 1100 FPS.

  • maodeedee

    Trading Mass for Velocity in most cases is a trade-off and a losing proposition. The 125 grain 357 projectile has been used successfully in thousands of actual street shootings, so if something isn’t broke why fix it? The potential success of the ARX light-for-caliber increased velocity projectile is a clever gimmick, but it’s possible utility is only based on theory and the fact that it makes impressive wound channels in blocks of Jello. –whoop-de-do. Shoot some wild hogs with it and then see how it works in the REAL world.

    The projectile’s shape may have some merit but wouldn’t it work just as well if not better if it weighed 125 grains and was a full metal copper jacketed lead projectile? But then that’s not what the ARX company is trying to sell us, is it?

  • Phil Elliott

    Has anybody heard of real world street shootings with this Bullet?