Umarex ARX Ammo for Air Rifles and Muzzleloaders

Umarex ARX Airgun Ammo

Umarex ARX Airgun Ammo

Umarex announced new ammunition for airguns and muzzleloading. Utilizing PolyCase ARX technology the Umarex  ARX SpeedBand and SpeedBelt bullets are to bring a new era of terminal performance to the air rifle and black powder hunter according to Umarex.

Manufactured using an advanced polymer-copper matrix, the ARX bullet has been available in pistol caliber ammunition from PolyCase with it’s Inceptor and the Ruger ARX brand. Now the non-expanding ARX ammo will bring it’s terminal performance to mid and large bore air rifles when combined with the Umarex SpeedBand or SpeedBelt polymer sabots.

The Umarex SpeedBand sabot is combined with either .357, .40, or.45 caliber Umarex ARX ammo and the SpeedBelt sabot is designed to be used with .50 caliber muzzloaders or air rifles with the Umarex ARX ammo. The sabot technology is not new, but for those who are unaware the polymer sabot “shoe” holds the sub-caliber projectile in the bore of the gun, ensuring a gas seal in the rifling of the barrel. The sabot falls away from the projectile after existing the muzzle.

The lightweight ARX projectile, combined with the sabot technology will propel the ARX to high velocities. This allows the ARX to consistently allows for superior terminal performance via the Venturi effect.

For more information please visit the Umarex website.



Scott is a firearms enthusiast and gun hobbyist whose primary interest is the practical application of gun ownership. In addition to contributing to The Firearm Blog, he hosts and blogs for The Firearms Podcast, a podcast and blog about gun stuff by gun people. Scott is a 20-year veteran of the USAF and been a member of his base, state and the All Guard marksmanship teams. He can be reached via email at


  • marathag

    This allows the ARX to consistently allows for superior terminal performance via the Venturi effect


    • Vhyrus

      The copy paste monster strikes again.

      • Dr. Longfellow Buchenrad

        Thats the “I ought to reword that sentence but not proofread the whole thing whem Im done” monster. Trust me he never leaves me alone when Im writing.

    • Patrick R. – Senior Writer

      It has been a long day. Most of us have been up and working since 6.

    • georgesteele

      I think the intent was to (in real English) reflect on the terminal ballistic performance of the ARX bullet, which, it is claimed, uses the “Venturi Effect” to increase shock. The sculpted bullet nose is supposed to redirect body fluid radially out from the spinning bullet – which at the higher velocities (and therefore rotational speed, for a given twist rate) of the lightweight bullet are said to produce a larger impact cavity,

      • User

        Except that it doesnt work at airifle velocitys.

        • georgesteele

          Not necessarily so; discount the velocity, and focus on the rotational speed. At even 700 f/s, a projectile out of a 1:12 twist barrel is spinning at 700 revolutions per second – not minute. That’s 42,000 rpm. The ARX bullet grooves are, theoretically, hydrodynamically designed to vector fluid outward based on that spin.

          Many tests of the ARX bullets in gelatin, (see YouTube) even at relatively low muzzle velocity, show a surprising amount of cavity expansion which it is hard to attribute to any other phenomenon, given a non-expanding projectile. When I say above “at the higher velocities”, I am referring to the fact that the ARX bullets are very light for size, and thus would be expected to have higher muzzle velocity than, say, a lead projectile out of the same barrel. That would be particularly so out of a muzzle loading black powder arm.

          Keep in mind that the Venturi effect applies to the acceleration of the fluid directed through the cavity in the bullet nose by the nose configuration.

          • User

            Do you notice something? 1:12 … The RPM doesnt matter. A bullet doing a single rotation in 12 inches and then magicly increase damage at such stupidly slow velocitys is hilarious.

            Also for the temporary cavity to even cause permanet damage (flesh tearing etc) it needs really high velocitys.

          • georgesteele

            You’ve made an incorrect assumption – that the bullet makes one revolution in 12 inches following penetration. That is not the case. Rotational velocity drops much more slowly than linear velocity. In the first few inches of penetration, the bullet is still spinning at 42,000 rpm. The rpm most definitely makes a difference. In 12″ of penetration in gelatin, the bullet does not make one revolution – it makes hundreds as it slows. This is visible in the gel tests – watch a few and then come back. For example, even in air, while linear velocity drops dramatically over a few hundred yards, rotational velocity is almost unchanged – which is why bullets expand against the compressive force of the target on the outer part of the ogive. As for permanent damage, think of the linear velocity of a .45 ACP, with a muzzle velocity of ~950 f/s, It does a lot of damage. In the early days of the .220 Swift, bullets sometimes tore themselves apart midair on the way to the target, until they made the jackets stronger – just from the stress of rotational forces.

          • User

            Still does nothing at airrifle velocitys. You need really high velocity for flesh tearing trough temporary cavity. And no “hundrets” is wrong too.

          • georgesteele

            “Hundrets?” What velocity are you assuming for an air rifle? If you are talking about pipsqueaks, I would agree, but you do understand the accelerative force doubling effect from a Venturi, right? If a Dragon Slayer can sling a 225 grain bullet at 600 f/s, or a Hammer can sling a 250 grain lead bullet at over 1,000 f/s, or a 550 grain at close to 900 f/s,what do you think the velocity would be with an 86 grain .357 or a 118 grain .45? Add to that the doubling effect of the Venturi. I think you have to go by observed results, not conjecture.

  • User

    Venturi effect in AIR rifles…..? You need far higher velocity to nearly get to that point.

  • Jake

    gimme a 1 7/8 oz 10 gauge one

  • Dickie

    Are there gunna b fewer posts today cause of this BS holiday?

    • yodamiles

      Today is SHOTSHOW media day. Just wait for crap ton of article later in the day

      • Dickie

        Nice. Forgot about that. Gimme info on the hudson h9

  • Don Ward

    This is the silliest firearm related news of the week. Granted it is only Monday and not even 9 am my time…

  • TechnoTriticale

    So not for .177 or .22, which is the bulk of the “airgun” market.

  • noob

    anybody able to do a gel test with a muzzle loader?