US Army Patents Limited-Range Projectile

"The image above accompanies U.S. Patent 9,121,679 B1, "Limited Range Projectile," awarded on Sept. 1, 2015. Brian Kim, Mark Minisi and Stephen McFarlane from Picatinny's Small Caliber Munitions Team are the inventors."

Apropos of Nathaniel F’s recent query: “How Can We Break The Small Arms Plateau, an interesting development may be taking place alongside the new prospect of guided (DARPA’s EXACTO and Sandia’s self-guided bullet) small arms ammunition: limited range rounds that aerodynamically destabilize at a set range.  Much like DARPA’s EXACTO, proof of concept is being tested with .50 caliber rounds at first.  The safety capabilities of a round that limits its ballistic trajectory come to thought at first, not only limiting collateral damage in urban combat, but opening up more (military) range possibilities for heavy caliber usage.  Others questions arise as well: Would this round be banned from civilian ranges due to its pyrotechnic nature?  Can these rounds ignite fires?  Would they be considered an explosive?  Should they be mandatory for celebratory gunfire or given away as a door prize at certain weddings?  (Slightly kidding with those last ones…)  Press release from Picattiny Arsenal follows:

PICATINNY ARSENAL, N.J. — Three employees of the U.S. Army Armament Research, Development and Engineering Center, or ARDEC, were awarded with a U.S. patent for their proof of concept work on a limited range projectile.

Brian Kim, Mark Minisi, and Stephen McFarlane filed collectively for the patent on May 7, 2013 and were notified of its approval on Sept. 1, 2015.

The concept for the limited range projectile includes pyrotechnic and reactive material. The pyrotechnic material is ignited at projectile launch. The pyrotechnic material ignites the reactive material, and if the projectile reaches a maximum desired range prior to impact with a target, the ignited reactive material transforms the projectile into an aerodynamically unstable object.

The practical use that the three men intended to apply the concept to .50 caliber ammunition. However, the patent covers the idea and technology behind the concept as a whole so it could theoretically be used in various calibers of small arms munitions.

“We wanted to protect the U.S. government’s interests and position,” McFarlane said about filing the patent.


Computerized modeling and simulation were performed to compare the inventive projectiles to the .50 caliber M33 projectile and the .50 caliber M8 projectile.

“Conceptual designs were ran through and evaluated via modeling and simulation,” Kim said. “Three concepts were submitted with the patent, however, not all were feasible,” he said.

“A proof of concept test was perfected and results indicated the need for concept refinement and pyrotechnic mix improvement,” Kim said.

The group states that there are significant benefits to the warfighter in using a limited range projectile.

“The biggest advantage is reduced risk of collateral damage,” McFarlane said. “In today’s urban environments others could become significantly hurt or killed, especially by a round the size of a .50 caliber, if it goes too far.”

McFarlane said that the distance in which the round disassembles can be adjusted based on the choice of reactive material used. The benefit to this is that the round does not continue to travel, therefore reducing collateral damage.

This benefit can best described as “a design programmed maximum range,” McFarlane said.

The ballistics also match and or exceed the standard round out to the max effective range of the round. In theory, the projectile may be any caliber from 5.56 mm to 155 mm.


The concepts vary, however in theory the process would work like this:

During launching of the projectile, pyrotechnic initiating material is ignited by energy produced by propellant in the cartridge case. Or, pyrotechnic initiating material may be ignited by energy produced by bagged propellant, if the projectile is a separately loaded projectile.

Pyrotechnic initiating material ignites the reactive material. Prior to impact of the projectile or with a target, and while the projectile is airborne, energy produced by the ignited reactive material transforms the projectile into an aerodynamically unstable object. The transformation into an aerodynamically unstable object renders the projectile incapable of continued flight.

In one concept, the projectile is rendered unstable by the melting of the copper jacket, which produces a highly irregular shape. In another, the projectile is rendered unstable by the separation of the cylindrical portion from the base portion and the separation of penetrator from the projectile assembly.


Currently, funding for the project has ceased. However, engineers hope that their concept will resurface as the constant need to provide greater technology for the warfighter increases.

Despite the lack of funding, McFarlane said, “This was the first patent we applied for that has been approved. That in itself is an accomplishment.”


Per Army Regulation 27-60 which deals with “Intellectual Property,” Government civilian employees and military personnel may be considered for an initial award of $200.”

They may be considered for a final award of $500 if certain conditions apply outlined in the regulation.

In this instance, since there were more than one applicant, “When two or more eligible persons are co-inventors, each will receive an initial award of $200. The final award to each eligible co-inventor will be $250.”

The concept for the limited range projectile came to fruition when the small caliber ammo development team was funded to investigate the feasibility of a pyrotechnically actuated disassembling limited range .50 caliber bullet.

“It was essentially my idea to create a self-destructing small caliber round akin to the larger caliber ones,” Minisi said. “The type of reactive materials to use and how to test it was Steve’s idea.

“Brian was instrumental with executing the effort, particularly the modeling and simulation to confirm the concept,” he said.


The U.S. Army Armament Research, Development and Engineering Center is part of the U.S. Army Research, Development and Engineering Command, which has the mission to ensure decisive overmatch for unified land operations to empower the Army, the joint warfighter and our nation. RDECOM is a major subordinate command of the U.S. Army Materiel Command.

For further reading, the full patent can be viewed here.

Rusty S.

Having always had a passion for firearms, Rusty S. has had experience in gunsmithing, firearms retail, hunting, competitive shooting, range construction, as an IDPA certified range safety officer and a certified instructor. He has received military, law enforcement, and private training in the use of firearms. He is fortunate enough to have access to class 3 weaponry as well.


  • dave

    this could be like ghost in the shell. a delayed explosive round. bullet buries itself in the target and then explodes for maximum effect. theyre only “calling it” a limited range round. but if its large caliber its not burying itself in anything, just ripping it’s way through.

    • Darkpr0

      A delayed explosive is not likely to result in better performance. On soft targets you would want the bullet to explode as soon as you can get it to do so, as they pass through a good chunk of a human body before going off (See InRange TV Tests), s a delay is bad. On hard targets, the ability of the bullet to penetrate sufficiently to get the explosive into a more helpful position is limited, and you’d get better performance either from a straight AP round, or from a high-explosive shaped charge assuming the round is sufficiently sized.

      The closest thing to what you’re suggesting would be a squash-head explosive round, but that’s not really covered by the patent, or by new technology.

      • oldman

        Exploding bullets are banned under a at least one treaty.

        • Darkpr0

          And I’m sure the German and Russians soldiers killed on the Eastern Front of WW2 by explosive rifle ammunition are comforted by that. And the militants targeted by Mk 211 today in more current conflicts.

        • iksnilol

          Not quite, explosive projectiles with less than 40 grams of explosive are banned.

          • jcitizen

            Apparently the US is ignoring this rule, as the round is fairly common. I think they are mostly issued to snipers, but I seen them floating around other units, and even civilian hands. I think the idea is that since they are not fighting a “regular” war, they don’t have to abide by regulations pertaining to such warfare.

        • jcitizen

          Seems rather redundant when you look at all the exploding munitions used against personnel now. The .50 cal HEIAP green tip has a small spot of high explosive in it. Composition A explosive and zirconium powder which is also supposed to have a grey ring on it somewhere, but I’ve never seen it. The ones I saw probably lost that part of the paint to fully ID the ammo. They were hugely expensive on the civilian market. They make a pretty good ‘pop’ when they hit a target at the range.

      • jcitizen

        I always read that bullet tumble was an ideal way to increase lethality in a bullet. I’d think this would be a really good feature all around – kind of a win-win no matter how you look at it. It couldn’t be any more expensive that an APIT or M855A1 bullet, once you get full production costs under control.

    • AMX

      The description sounds rather non-explosive.
      Probably incendiary, though – at least the “melts the jacket” variant.

    • The Bellman

      …or a bolt round from 40k, just with less gyrojet.

    • Phillip Cooper

      It sounds to me like it’s intended to “disassemble” at one of two occurrences:
      -achievement of max effective range (in order to prevent misses from hitting someone a klick away, for example)
      -upon impact. (which now you REALLY don’t want to be hit by a 50… but you’ll never know it)

  • Kev

    I remember reading about reactive material ammunition instead of limited range it was to replace raufoss mk211 round don’t think anything came of it but it shows the be nifty of we projectile material.

    • Phillip Cooper


  • Sianmink

    Also not mentioned, since this is a time-based pyrotechnic, it could get a little ugly when it goes off inside a soft, wet target.

    • Well, it’s not like the standard .50 BMG was the paradigm of modesty to begin with.

  • Ben

    Frankly, time to stop wasting money on more and more weapons to prevent so called collateral damage. And put more on weapons that wipe out our enemies.

    • aka_mythos

      We’ve got everything from nukes to 5.56 so I think we’ve got the wipe out our enemies weapons pretty covered. What we have are an enemy that knows we are unwilling to wipe out non-combatants and use that to their advantage. Things like this and XM-25 deliver proportionate lethality, just as guided munitions have they mitigate the risk to innocent lives. Just War theory dictates for a war to be just it must be conducted with the minimal prudent force. This and programs like it allow us to use more of our weapons in situations where they would otherwise be excessive.

      • toms

        Spoken like a true academic. The reality is that we have not won a single war since we started pushing that doctrine. Limited warfare has lost us Korea, Vietnam, Iraq, Iraq 2, Afghanistan ect. If a war doesn’t need to be fought totally than its not a war that needs fighting. One day we will wake up and smell the PC bullshit. How much will this tactically useless ammo cost per round? Just the fact that this round type originated in Scandanavia tells me everything I need to know. Do Russia, China, Iran worry about collateral damage when they go to war?

        • aka_mythos

          Short of Russia’s take over of the Ukraine none of those powers have really won either. The Just War theory isn’t new either, it’s been the prevailing theory on ethical warfare since the 1200’s. WWII was fought under this prevailing theory, embraced as what distinguished us from the Nazis.

          There is an argument to be made about how worthwhile all these wars have been. A number of scholars believe its been our willingness to fight such regional wars that has alleviated the potential for global conflict. It may seem counter-intuitive but if the intent to prevent global conflict or escalation outside of a region, then you can still win the war even if your military campaign has failed.

          • RSG

            WWII was NOT fought with a Just War edict by any contributor. Japan tortured, enslaved and summarily executed everyone they could get their hands on. The British indiscriminately bombed everything they could fly over. And of course, we used the “Boys” over Nagasaki and Hiroshima. Once again proving that “total war” is the only legitimate pursuit of a war is worth fighting.

          • aka_mythos

            Philosophy isn’t necessarily a perfect or attainable thing, it is an ideological goal. If you believe a war must meet the criteria as opposed to just strive to meet the goal of a “just war” there has arguably never been a war fought under it.

            The nuclear weapons used on Japan to end the war… arguably very just when weighed against the believed potential for loss of life anticipated if the war had progressed to a mainland invasion. It exchanged a loss of life orders of magnitude greater for lesser one.

    • Perhaps our continued effort to wipe them out is why we have so many?

  • 624A24

    So this is a very defective tracer?

  • Jaedo Drax

    so they created a smaller version of the Sprenggranatpatrone L’spur mit Zerleger?

  • Kivaari

    I can see this used on the range. While qualifying at Fort Lewis (WA Joint Base Lewis-McCord) the .50 M2HBs had chains and a ring that limited the movement of the weapon. It prohibited elevation and lateral movement. The Army did not want us lobbing rounds into Yelm.

  • Kivaari

    Why use this on arty? A timed fuse and/or proximity fuse already exist.

  • Tom Currie

    Headline is wrong — and the article leaves out a lot. The Army didn’t patent this concept, because as an agency of the US government, the Army CANNOT patent anything. Letting three employees patent the “work for hire” in their own names is a thinly veiled end-run around the law. An end-run that would be voided if it ever went to court except that by now they will have passed the rights to their so-called patent to the Army and any attempt to invalidate the patent would be fighting the full unlimited budget of the US government.

    • Glenn Bellamy

      There is nothing “thinly veiled” about how this patent application was filed. In the US, every patent application has to be filed in the inventors’ name(s). In some cases, the inventors have a duty to assign patent rights for an invention created in the course of their employment to their employer. This is how it works and would not jeopardize the validity of the patent at all.

      • Tom Currie

        Try again, Glenn. When the “inventors” are people who have inventing a specific item as part of the duties of their employment, that invention is actually a “work for hire” in which case the intellectual property rights (patent and/or copyrights as the case may be) belong to the employer, not the individuals.

        BUT that only works if the employer is eligible to patent the invention. No federal government agency is eligible to patent anything — the legal basis is that because the federal government is entirely taxpayer funded, everything the federal government does is already the property of the people who paid for it. In recent years, the Army has become quite adept at obtaining intellectual property rights by ignoring that most of the items are works for hire and having them registered in the name of various individuals or contract companies, who then transfer “their” rights to the Army.

  • jerry young

    without even going to the civilian use side of this I see problems for normal military use, if you’re in a fire fight at say 100 to 200 hundred meters but your rounds are for 150 meters you then have to have a wide variety of ammo set for different ranges not a good choice, for a sniper they may be good but again carrying different rounds for different ranges you would be limited by how much ammo you can carry, this all sounds like a good idea but there are drawbacks to every good idea, this also sounds like a spin on the rockets we used in Nam in the 70’s that after being fired and after a certain amount of revolutions would arm the war head, another question since this concept is based on igniting the charge in the projectile upon firing would these rounds act as tracers?

  • zippiest

    I thought exploding bullets were against LoAC?


    Probably they were trying to extend the range of the rounds by giving them a simple rocket propulsion that would fire up half-way down the range, but the results were just the opposite: Rounds disintegrated or cartwheeled instead of accelerating. And then, someone must have said: “Hey, you know what, it’s not a bug, it’s a feature!”

  • This has so many problems. When a Bullet from a rifle gets unstable, it does weird things and goes in unpredictable directions. This is a bad idea.

    • AD

      That’s exactly what I was thinking. It seems to me that the projectiles aren’t going to just stop dead and fall harmlessly to the ground, they are going to continue traveling in an unpredictable direction, meaning that they can very easily go on to hit something. I guess they’ll shed velocity more quickly due an less aerodynamic shape, so range will be somewhat limited compared to a traditional bullet, but that hardly makes them “safe for use in an urban environment” or anything. If the projective actually disintegrated into sufficiently small parts, like birdshot or something, that might be a different story.

  • Austin

    Wasn’t a self detonating 12ga payload already developed?

  • VTR1

    Don’t the CRAM systems at Bagram already have rounds similar to this?

  • CavScout

    During MOB we used some sort of short range plastic ammo in the M2’s.
    How is this needed?