Why “Open Tip Match” ≠ “Jacketed Hollow Point”

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Over at WeaponsMan, Hognose broaches the subject of “OTMs” and “JHPs” and that they are not the same thing. He writes:

Okay, this is a post about ammunition, and especially, military ammunition, but it also has applicability to police and personal defense use. Now hear this, as the swabbies like to say: Open Tip Match ammunition is not hollow-point ammunition in the sense in which the latter is usually used, to wit, expanding ammunition.

OTM does not differ materially in its expansion and fragmentation from ball ammo. Therefore, it is according to the letter and spirit of the Hague Agreement, perfectly legal.

If an open-tipped match bullet looks like a hollow-point bullet, how does one tell the difference? How does each type perform, and what does “Hague compliant” mean in this context?

These are easier questions to ask than they are to answer, but I will give it my best go. My readers should keep in mind that I am not a JAG lawyer, and therefore anything I say that has legal implications must be taken only as my technical understanding of the subject, and not a declaration of legal fact.

With that out of the way, the first and most easiest answer to the first two questions is “JHPs are designed to meet hunting requirements, and OTMs are designed primarily for utmost accuracy, or in a military context, to meet terminal characteristics requirements.” The reader will note that “military terminal characteristics requirements” cuts both ways; an OTM may be designed to improve terminal effectiveness versus existing FMJs, but it must not do so in a way that violates the Hague. This means, it must have terminal characteristics essentially similar to FMJs, but those may be made more consistent or reliable.

The result of the accuracy requirement is that the jacket is drawn from the base of the bullet, rather than the front as in a conventional FMJ. From a manufacturing standpoint, the bullet is made to be loaded “backward”, and doing this can give several benefits for accurate shooting. Firstly, lead can be inconsistent in form when loaded into a jacket; this means that to achieve the highest consistency, the base of the bullet should be made of harder stuff that can be more consistently shaped into a smooth, even surface. The jacket material is an obvious candidate for this.

In addition, moving the jacket opening (where the core material must be inserted from; on the base in conventional bullets) to the nose provides concentricity advantages. It is difficult to get the edges of the jacket of a bullet perfectly radially symmetrical, and these differences in radial symmetry help create inconsistencies and stability issues when they are further out from the central axis of the projectile’s rotation, as in a conventional FMJ projectile. The OTM design alleviates this greatly by moving the jacket opening to the meplat of the projectile nose, and therefore “closing up” the opening considerably. Some OTMs even take this a step further, and deliberately close the jacket’s opening all the way, with a die.

Doesn’t all this de-facto create a JHP? Sure, maybe it’s done for accuracy reasons rather than to make the bullet drop whitetail better, but doesn’t the opening in the tip of an OTM act for all intents and purposes as a hollowpoint, and doesn’t that imply that OTMs are being used in a military setting with an implied emphasis on their improved terminal effectiveness, with the ostensible reason being “improved accuracy, nudge nudge wink wink”?

Not really. As we’ll see, the OTM has substantial differences to the hunter’s jacketed hollow-point or soft-point bullet. Chief among these is the lack of provision of any striations on the jacket that would facilitate failure points in it, allowing the bullet to “petal” and expand. Most commercial jacketed hollow-point projectiles feature these striations, either internally or externally, and all projectiles approved for general issue by the JAG do not feature them. Since the Hague prohibits:

[T]he use of bullets which expand or flatten easily in the human body, such as bullets with a hard envelope which does not entirely cover the core, or is pierced with incisions.

These striations are therefore not Hague-compliant in the normal understanding of the agreement.

The performance of OTM bullets also more closely resembles that of normal FMJ projectiles than hunting JHPs and JSPs. A standard FMJ projectile may exhibit a combination of tumbling, axial flattening, and/or fragmentation, all of which are accepted as being Hague-compliant terminal characteristics for bullets used in war.

SteelJacket

An example of how FMJ bullets perform in tissue. In some cases, the projectile only flattens axially at the cannelure, however some shots fragment, producing more dramatic results. Image source: ar15.com

 

A well-designed hunting JHP does not exhibit this kind of fragmentation or flattening. Hunting JHPs are designed to frontally expand while remaining stable and, most importantly, intact. In service of this last, the most effective JHPs bond the jacket to the lead core, either mechanically or chemically.

7mmNP-bullets1

Examples of hunting JHPs. The red arrow points to the terminus of one of the internal striations on the middle bullet, which allows it to neatly expand with the characteristic “petals” of a JHP. The flanking rounds also exhibit JHP-type performance, though they may not have purpose-cut striations. Image source: rathcoombe.net

 

How do two common OTM-type projectiles compare to these two types? OTMs typically perform very much like FMJs with comparable jacket thickness. Modern Sierra-type OTMs, however, typically use a thinner jacket of about 0.35mm compared to the 0.50mm+ jacket common in military FMJs. This doesn’t drastically change their performance, but it does reduce the velocity needed to induce fragmentation.

77grchart

Fragmentation of the 77gr Nosler BTHP. This projectile has been loaded in military Mk. 262 ammunition, and is very similar to the Sierra 77gr BTHP. Note that both Nosler and Sierra bullets are called “Boat Tailed Hollow Points” despite meeting the definition of an “OTM”. Image source: ar15.com

 

Major efforts to improve the consistency of terminal effect of OTMs have been undertaken, resulting in part in the Mk. 318 round, which is largely supplanting the Mk. 262 in service. This round combines the fragmentation capability of the thin-jacketed OTMs with additional penetration from a solid rear half, while incorporating the yaw independent characteristics refined through the M855A1 program.

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This fired Mk. 318 SOST OTM projectile illustrates the typical performance of the round in tissue. The jacket quickly loses integrity, separates from the base, and fragments like a standard FMJ, while the solid gilding metal slug continues on, providing additional penetration and insurance against barriers. Image source: sadefensejournal.com

 

The Mk. 318 SOST in particular has become controversial primarily due to its resemblance to a commercial hunting projectile, the Trophy Bonded Bear Claw, offered by SOST producer ATK’s child company Federal. However, the two bullets have considerable differences: The SOST round lacks the bonded construction, thicker jacket walls, and wide, exposed lead tip of the TBBC, while the Bear Claw lacks the thin jacket at the cannelure of the SOST round. This last feature induces fragmentation comparable to military FMJ projectiles such as M193 with a lower required velocity.

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The Mk. 318 SOST compared to the untipped Trophy Bonded Bear Claw projectile. While their construction is broadly similar, the TBBC features an exposed lead tip of much greater diameter than the Mk. 318 OTM, thicker sidewalls, and a bonded core and jacket. These differences are highlight how subtle changes in a bullet’s construction can lead to very different terminal performance characteristics, evidenced by the neatly mushroomed TBBC on the far right. Image composited from images found at sadefensejournal.com and neveryetmelted.com

 

The wording of the 1899 Hague Peace Conference does prohibit two characteristics that are widely used in warfare: Bullets which “flatten easily” and bullets “with an envelope which does not entirely cover the core”. Virtually all FMJ spitzer projectiles flatten easily in tissue, “pinching” easily at their waists as they tumble in tissue. The 1899 Hague could not have known about these later developments, however, as the first high velocity spitzer projectile to enter service had only done so a year before, and it would be another six years before jacketed lead-cored spitzers were popularized by the Germans. The construction of these bullets was identical to the older FMJ round-nose projectiles, but their terminal characteristics were different, something that was not fully understood until after World War II.

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Some of the types of projectiles prohibited by the Hague Peace Conference of 1899. Cartridge number 3 makes it very obvious what the wording “piercings or incisions” was meant to prohibit. Image source: semperfidelis.ro

 

So the high-velocity spitzer FMJ has to get a pass; it was invented after the Hague, and not understood to be violating the letter of it until well after they had become ubiquitous in use. Since all the Hague nations use it, it’s not a problem.

Which brings us to the “envelope which does not entirely cover the core”. It’s more clear what this refers to; the Hague does not prohibit the round-nosed FMJs that were common at the time, which do have an exposed opening at the rear, the common “dum-dum” improvised round had a large section of its jacket removed, exposing the lead core underneath. Later factory rounds would partially cover this core, but still expose a large hole through which the lead could expand or separate from the jacket. The wording of “entirely cover” is still ambiguous, but the expanding rounds that were available at the time give some insight into the intent of the Hague authors. A standard OTM covers its core, and even though there is an opening in the tip of the projectile, a reasonable application of the Hague prohibition could exempt OTMs.

Despite this explanation, the nomenclature used by commercial entities continues to cloud the issue. As previous mentioned, both Sierra and Nosler call bullets legally classified as OTMs “Boat Tailed Hollow Points”, and many other manufacturers make bullets that perform identically to OTMs (though they may not be constructed in the same way) without qualifying in the most technical sense as either OTMs or JHPs. These, too, are often called “hollow point” rounds, despite the fact that they neither expand, nor do they have the characteristic closed base of modern match bullets. It’s not a problem to call these rounds “hollow points”, so long as it is understood that they don’t perform in such a way that violates the 1899 Hague.

One thing this segment does not cover is pistol-caliber hollow point ammunition. Because that ammunition is designed for much lower impact velocities than rifle ammunition, only the most fragile projectiles will fragment to any degree, and therefore the vast majority of open-tipped pistol projectiles fall squarely outside the Hague’s limits. This is the reason there has been little development of pistol-caliber OTM equivalents for military use.

I will close with another quote from Hognose’s article on the legal implications of these differences:

If your objective is not to aggravate the wounding effect or suffering, and the round does not have that effect (as is the case with OTM which has, as well documented by Parks and elsewhere, expansion and fragmentation statistically indistinguishable from FMJ ball), then your round is legal, full stop.



Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. In addition to contributing to The Firearm Blog, he runs 196,800 Revolutions Per Minute, a blog devoted to modern small arms design and theory. He can be reached via email at nathaniel.f@staff.thefirearmblog.com.


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  • Vitor Roma

    I think it is really a non-issue for the sakes of common sense, because it is absurd to to think it is “more ok” to be shot since the bullet is a fmj and not a jhp or whatetever.

    • Right; it’s real relevance is to making a determination on Hague compliance, and to understand how each type works differently.

      • Vitor Roma

        I see, but I find the Hague Convention downright stupid. Oh, so nice that 8×57 4k joules of energy hitting me is not a hollow point, so humane.

        • Joshua

          well that’s fine since the American’s completely ignore the Hague anyway. chemical warfare ban? yep that’s ignored, treatment of prisoners? yep no regard there. Landmines? yep the USA is still developing new ones.

          • Which is why it’s strange that the US military legal system still anguishes over it for small arms ammunition, yes.

          • Kivaari

            Land mines are legal. America and some allies are testing self-destruct mines. Either by blowing up or shutting down the firing mechanism, Chemical weapons? Haven’t we already destroyed them? We do use teargas.

        • Exactly how an expanding hollow point is less humane than a fragmenting M193 ball round is a bit beyond me, I agree.

        • RealitiCzech

          It’s also perfectly legal to use flamethrowers… so it is more humane to burn people to death than to shoot them with a hollow point.
          Makes perfect sense.
          Does anyone have a mini-flamethrower I can mount to the rail of my pistol?

  • Vitsaus

    Great article!

  • Lawrence Glorioso

    If my memory is not too faulty, this section of the treaty applies only if the opposing force is also a signatory thereof. Since terrorists are not a signatory, the rule is not applicable.

    • Randy Vooty

      You would be correct.

    • Esh325

      But most countries abide by it anyways.

    • Paul Epstein

      Or, for that matter, once a group who is not a signatory joins the conflict (on either side). The Hague conventions seems to be one of those odd treaties that is actually treated as more restrictive in practice than the wording would indicate.

    • Andrew

      And I don’t think the US signed that portion either, so this ‘law’ appears irrelevant to me. But Im no lawyer.

  • Slim934

    If you have already accepted the premise that hurling metallic objects at high speed from a manportable weapon is already fine and dandy, then what is the premise of saying “the bullet can only kill by hitting in THIS way”? What exactly was the idea behind having such a dumb proviso? If we were not bound by this convention I feel like we would have vastly better performing ammunition.

    • Vitor Roma

      Well, Im a libertarian, so I really dont care about the military having nice ammo, as long civilians can get their inhumane lehigh bullets, im fine. =D

      • Slim934

        Well that’s essentially it for me as well. If the state is going to dump my money into various military boondoggles I would atleast appreciate them dumping it into something which may actually help me at some point.

      • Sadlerbw

        I always found it befuddling that American police were legally allowed to shoot American citizens with hollow point bullets, but American soldiers can’t shoot enemy combatants with them. It seems that any bullet we are willing to use on ourselves ought to be plenty humane to use on the enemy. The law is certainly a funny thing.

    • I’m not sure our ammunition would be so much better, but there would certainly be more options for projectile design.

      I think the Hague comes from a time when technology was changing quickly, and there were serious worries about improved weapons increasing pain and suffering. Given what happened later in World War I, I’m not sure that worry was unjustified.

      The ammunition restrictions that today seem pretty silly are a byproduct of that thinking.

      • Slim934

        In other words it was scare-mongering. Trumping up a perceived evil or possible future evil without doing any work to verify if that reasoning is really accurate. I figured that was the case and was just curious if anybody else knew anything different.

      • Esh325

        I think they wouldn’t have ran into the problems they did with the 5.56×45 if were able to use true expanding ammo.

        • I disagree. JHPs or no, M855 would still have been adopted by NATO.

    • Marc

      The idea is that a wounded soldier is just as incapable to fight as a gruesomely maimed soldier.

      • BillC

        No. That’s a myth that doesn’t seem to die. The military is not in business of wounding or tickle fights. It is in the business to kill and destroy. Intentional wounding is he thing of bad war movies.

        • The Believer

          No, shooting to wound is a myth regarding what police should do that will never die.

          Weapons that will either reasonably often incapacitate but not kill- thus causing further soldiers to be withdrawn from the field to evacuate the wounded- are a long term goal of military strategists, and have been for a long, long time (and always will be).

  • Marc

    The “open tip match” is called “hollow point boat tail” by its producer. The hollow point of a HPBT may not be specifically designed to initiate expansion, but it’s still a hollow point. Selecting a bullet specifically for fragmenting, which thin-jacketed HPBTs, especially with cannelures, are known for, isn’t really that much different either.
    Hate all you want, you know it to be true. Funny that the most hate usually comes from people who don’t care for the Hague convention anyway.

    • Semantics aside, one is Hague compliant under the normal understanding, and one is not.

      No “hating” here. 🙂

  • Lance

    Mk-318 is the best round outside of M-193 ball in use by the military. As for the Hague peace Conferince I say its outdated our Muslim enemy didn’t sign it so heck with it.

    1899 Hague Peace Conference

  • Southpaw89

    Well this explains my confusion about that 9mm round that we saw in an earlier post.

  • Kivaari

    The 7.62x51mm was extensively tested by the US Army. The OTM bullets, Sierra Match Kings, did not expand. One widely distributed incident was the shooting of Randy Weaver.
    When our civilian LEOs (DEA) were sent to the sandbox, they used commercial expanding ammo, Federal tactical. It worked very well.

    • The Believer

      Randy Weaver was never shot.

      Federal agents killed his wife and 14 year old son from ambush, and walked. Horiuchi walks among us to this day, like a human being.

      No politics, just the facts mam.

      • Kivaari

        It’s wquite odd that I read the official reports and the wound ballistics report of Weaver being shot through his shoulder, with a .308 Federal 168 Gr. Match King. There was considerable reporting on the ineffectiveness of the 168 OTM load, and how to improve it by using a fine drill to open the tip.
        You may want to read it is Wound Ballistics Review. Weaver was going to an out building where his sons body was placed. Randy suffered a through and through shoulder wound. The shooting of Weaver and his wife were extra-constitutional. Even FBI Director Freeh admitted it.

  • Blake

    awesome article, thanks

  • Zebra Dun

    The old Marine Kinder, gentler NaPalm argument.

  • lostintranslation

    Nathaniel, I have a couple of questions:
    Has the Mk318 Mod 1 bullet been formed around a ‘mandrel’ that leaves weaknesses within the bullet, ‘hollow point,’ to enable improved terminal ballistics?
    The manufacturing process (drawn from the base) may not necessarily require a hollow point to be left in the bullet. Why has the choice been made not to close the ‘hollow point,’ during the manufacturing process?
    For those who are seemingly against the Hague Convention 1899 and subsequent, would they then countenance explosive tipped bullets to help defeat body armour?
    Perhaps an explosive tip in conjunction with a small quantity of poison might be acceptable to ensure that even a CASEVAC for a minor wound would be pointless.

    When you remove a constraint you can never be quite sure how the story will unfold. Also, what goes around comes around.
    Has everyone given full consideration to possible outcomes and the Law of Unintended Consequences?

    • I’ll number the questions in the order you asked them, for clarity, lost.

      1. No, I don’t believe Mod 0 or Mod 1 have any internal weaknesses of the kind that typifies JHP rounds. I have sectioned Mod 0, but I have not sectioned Mod 1.

      2. Probably cost, as well as giving it a frontal failure point for added terminal consistency. I think also that the bigger that opening is, the wider a die you can use to punch the jacket into shape, which means that die lasts longer and you don’t have to replace it as often. Very important for a high-volume round.

      3. Right, JHPs are not materially different to other rounds, but remove the Hague entirely and you can do silly things like potentially fire explosive projectiles from your infantry rifles, which is certainly its own can of worms.

      • lostintranslation

        Nathaniel…

        I would like to add a few aspects for consideration and hope that they might assist in the discussion.
        If we take the following from Wiki:

        As the issue of environmentally friendly ammo grew, the Marines looked to see if the Mk318’s lead could be replaced while still meeting specifications. They found that by replacing the lead with copper and slightly stretching the jacket around to crimp the nose even more, the bullet’s ballistic coefficient increased.

        “Stretching the jacket around to crimp the nose even more,” indicates that closing the hollow point improves the ballistic coefficient.

        Again from Wiki:
        “When a hollow-point hunting bullet strikes a soft target, the pressure created in the pit forces the material (usually lead) around the inside edge to expand outwards, increasing the axial diameter of the projectile
        as it passes through. This process is commonly referred to as mushrooming, because the resulting shape, a widened, rounded nose on top of a cylindrical base, typically resembles a mushroom.”

        Why is the hollow point there in Mk318?

        The answer appears to be; that if you remove the hollow point, the terminal ballistics of the Mk318 are degraded.

        The hollow point appears to enable the ‘front’ section of the bullet, defined by the hollow point, to ‘shatter’ under the pressure wave in the ‘cup.’ The mushrooming effect might, effectively, be ‘a prior state.’ Put another way, the expansion mushroom might occurs prior to the shattering of the bullet tip.

        The bullet tip is; “not specifically designed for expansion.”
        The bullet tip appears to be designed to shatter within the target. It is, therefore, somewhat disingenuous to suggest that the hollow point has no effect on the terminal ballistics.

        What if the reverse drawn manufacturing process, of the bullet, could be shown to be achievable without the requirement to leave a hollow point?
        Would there subsequently be an admission that the hollow point is essential for the impact pressure wave to shatter the tip?

        There are a number of camera systems with very high frame rates (1million frames per second up to 10 million frames per second) that would reveal the actual impact process that occurs.

        Examples can be seen on YouTube with the following search:
        1 million fps Slow Motion video of bullet impacts made by Werner Mehl from Kurzzeit.

        It is quite possible that those who formulated the Hague Convention 1899 and subsequent, did not consider the possibility of a bullet with a shattering front section. Their thoughts were perhaps in regard to mushrooming and measurable expansion.
        However, is there a mushroom expansion effect that is a precursor to the shattering effect?

        I apologise that this is a somewhat long reply.
        For those who may be interested I have appended below a brief extract from: The Accidental Guerrilla by David Kilcullen (Oxford University Press).
        I hope that those reading this will appreciate that my objective is not to flippantly weaken the US position and cost lives, but; to request a reasonable consideration of the Law of Unintended Consequences:

        “……..the United States currently possesses a degree of
        military superiority in conventional capability that is unprecedented
        in world history. No other country, or combination of countries, could expect to take on the United States in a conventional force-on-force
        engagement with any prospect of victory. This is underlined by the enormous scale of American defense spending: according to recent unclassified estimates, the U.S. defense budget accounted for 54.5 percent of total global defense spending in 2007, with the other 45.5 percent representing every other country on Earth combined.
        In mid-2008, counting supplemental budget allocations for the Iraq War, the U.S. defense budget is approaching 70 percent of total global defense spending.
        The second implication of this massive asymmetry is that because its
        military superiority gives the United States the capability to destroy any
        other nation-state on the face of the earth, belief in the fundamentally
        benign intent of the United States becomes a critical factor in other countries’ strategic calculus. Intelligence threat assessments typically examine the twin factors of capability and intent, focusing on capability because intent is subject to much more rapid and unpredictable change. But the destructive capability of the United States is so asymmetrically huge visà-vis every other nation on Earth that it poses what international relations theorists call a “security dilemma.” Unless other countries can be assured of America’s benign intent, they must rationally treat the United States as a potential threat and take steps to balance and contain American power or defend themselves against it. And efforts to improve U.S. military capacity, which American leaders may see as defensive, may therefore have a negative overall effect on U.S. national security because of the responses they generate. Again, this reflects Qiao Liang’s insight that unless other countries trust the United States (that is, unless they believe it will follow its own self-imposed rule-set), the whole basis of international cooperation tends to be compromised. Thus the widely observed phenomenon of countries “bandwagoning” or engaging in balancing behavior against the United States, along with countries seeking nonconventional means of attack and defense, may not necessarily indicate hostile intent on these countries’ part but rather it may simply be a rational response to overwhelming U.S. conventional military capability.
        Nor is such anti-American behavior necessarily a sign that
        the United States is doing something wrong: rather, it may simply be an inherent structural aspect of a unipolar global system, a security dilemma representing an inbuilt pattern that would have occurred whichever nation found itself in this position. Such thinking might suggest that American primacy, like the primacy of any other nation beyond certain limits that other nations find acceptable, could be inherently destabilizing of the global system and thus harmful to America’s own interests. It also suggests that assuring other nations that the United States will exercise its power responsibly, sparingly, virtuously, and in accordance with international norms is therefore not an optional luxury or a sign of moral flaccidity.
        Rather, it is a key strategic requirement to prevent this previously noted
        adversarial “balance-of-power” response to the unprecedented scale of
        American military might. American power must be matched by American
        virtue, or it will ultimately harm both the United States and the
        global system.”