Testing the Duckbill Choke with Matt Haught

Today I am out at the range with Matt Haught of Symtac Consulting to test out a duckbill choke. Also known as a spreader, this was a muzzle device used briefly by SEALs in Vietnam – the idea is to spread shot in a horizontal oval pattern instead of a circular pattern. This improves the likelihood of hitting a hidden or moving target at ground level. The original devices were not all that well made, and tended to crack and widen under the repeating impact of use. The one I have today is a hardened reproduction made by Chuck Madurski and Kevin Dockery many years ago. It was fitted to a Remington Model 11 barrel for me by Vang Comp (who also installed the extended magazine and handguard). Matt and I are going to try out three sizes of buckshot; #00, #1, and #4 at 10 yards to see if the duckbill actually does what people claim.

What we found was that the device works best with #4 shot, with marginal effectiveness using #1 and no effect with #00. We saw a shot pattern of rough 3:1 width to height, with the height being approximately equal to the diameter of a plain cylinder bore gun used as a control. At 25 yards, this resulted in a pattern more than 3 feet wide, hitting multiple side-by-side silhouettes.


  1. A very interesting test, and I do like the behemoth Vang-Comp’d Rem. 11! The roaring 20s and Depression-era 30s saw very, very many Rem. 11s in use that is for sure.

    My understanding is that in the counterinsurgency in Malaya, the British colonialists employed a bone-stock long-barreled Auto 5 loaded with nine pellet 00 buck in the counter-ambush role. This usage was supplemented by the Rem. 870 as well, which was also supplied to ethnic Malay auxiliaries alongside the suite of British and Australian infantry arms. The point man would basically do a “mag dump” at contact. There were complaints and concerns about reloading time of the tube magazine, but I suspect that tactical reloads through the open chamber were a norm. This usage in the counterinsurgency against the MRLA communist rebels generated a relatively detailed report on the use of the shotgun as a jungle fighting weapon. Broad-arrow marked “SG/LG” buckshot shells are known to have been issued out to the original “parashots” and LDV/Home Guard volunteers in Britain, and many Home Guard publications are enthusiastic about the potentialities of using shotguns in house-to-house fighting or at roadblocks against the Boches. Also, a “pumpkin ball” slug was developed such that it could be used in fully-choked Limey fowling pieces.

    In Vietnam, my understanding is that the concern was to use No. 4 buckshot to produce a denser pattern at longer ranges. Of course, as shotgunners know, the pattern of buckshot eventually opens up to the point that few if any pellets remain on target. No. 4 buckshot was also used by urban police departments, concerned as they were with overpenetration using the “All ‘Merican” 00 buck that had garnered quite a reputation as a “fight stopper” in the roaring 20s and Depression-era 30s. 00 buck was used around vehicles. No. 4 in urban settings. This led to studies of the No. 1 buck, which suggested it might be an “optimum” of 16 pellets to the 8 or 9 00 buckshot pellets. Legal ramifications led agencies to move away from shotguns all together. My understanding is that the FBI first went to a “slugs only” policy for shotguns, and for years now only does familiarization training with the hoary old 870. But for civilian use, or for breaching by door knockers, the days of the shotgun for defensive or antipersonnel use appear to be mostly over.

    I will also note that Leroy Thompson did some work with an ex-SEAL naval Ithaca 37 gun, and even demonstrated holding it such that the oval pattern extends “north south” on a vertical rather than “east west” horizontal plane.

  2. In the classic film ‘The Life and Death of Colonel Blimp,’ there’s a scene where Roger Livesey arrives at his post-Dunkirk emergency HQ and stops to advise the sentry, who is armed with a scavenged shotgun. ‘Number 4 shot!’ he declares.

    I think I read somewhere that the FBI issued #4 as well.

  3. Are there any “running boar” ranges in Arizona. Basically you have a paper target of a wild boar running on rails between two berms. The target is only exposed for 2 or 3 second. “Running Boar” used to be a popular “warm up” for German hunters. My dad brought the concept to Canada during the late 1960s and build a “running boar” range at the Sand Hill Rifle Club, Quebec.

  4. Read “Pointman” by Patches Watson. He writes in his book about using one in VN.
    I had one installed on a Mossberg 500 back in the late ’80s by a company called Great Lakes Armory. They had never done a 500 before and agreed to do my slug barrel as a test. When I got it back the accompanying letter, besides thanking me for letting them test/mount the Duckbill, stated that they wouldn’t do any more 500s due to the complexity of machining to fit around the front sight.

  5. More shotguns!

    Thanks Ian, for this interesting look at the duckbill choke system. Looking forward to the moving target test.

    I have a suggestion for another shotgun experiment. This experiment might be of interest to you because of your prior testing of rifles shooting 7.62x51mm duplex-bullet load ammunition.

    This shotgun experiment might be too niche, but I’ve wondered at the potential of the 000 buckshot load in the .410 shotgun as a kind-of poor-mans Project Salvo weapon. In theory four pellets of 000 buckshot would have good enough penetration and low enough dispersion for practical antipersonnel uses out to 100 yards range. The Federal 4 pellet load or the Winchester 3 pellet load seem promising candidates for this purpose. The long 3 inch shell with 5 pellets does not seem promising.

    What makes this concept even more intriguing are the detachable magazine semi-automatic .410 shotguns now available, such as the .410 uppers for AR-15, which can use the 2.5 inch .410 shotgun shells. A .410 AR with red dot sights and detachable magazine might be practical. Weight of ammunition isn’t too bad either, with similar ratios of projectiles to weight of 5.56mm rifle ammunition. Even the small 5 round detachable shotgun magazine with the Federal .410 shell puts out 20 projectiles in a magazine of similar size to a 20 round 5.56mm magazine.

    I suggest moving target tests at 25 yards, and dispersion tests at 50 yards as initial experiments. What might make the experiment even more interesting is using a 9mm SMG fired full automatic as a control weapon.

    • Lever-action .410 that’ll take 2-1/2in. .410 shells loaded with four x 000 buckshot pellets at 1225fps. I’m pretty sure these are really 00, just as lots of “00” when measured turn out to be “0.”

      Also, with the “spreader choke” if not an actual “duck bill” already installed on the Mossberg HS .410, that would be a good pump-action Mossberg 500 option.

      I might point out that a round lead pellet is a “projectile” but a 55gr. or 62gr. 5.56mm hyper-velocity small caliber bullet is a *bullet* and vastly more destructive than any lead sphere let alone SPIW “flechette” micro-dart…

      Winchester did develop a prototype 26-gauge submachine shotgun, that was supposed to fire flechette shells.

      • Dave “vastly more destructive than any lead sphere let alone SPIW “flechette” micro-dart…”

        IIRC (SPIW was before my time and I haven’t studied it deeply) the idea was to kill via hydrostatic shock, not physical destruction – the same method attributed to the 5.56mm in its early days

  6. Mr Haught mentioned were intended for close range combat.
    What sort of range is that ? How lethal are these loads out to what range? Most of my shotgun experience comes from watching “Bullitt” with Steve McQueen.

  7. There were a couple of other “shot diverters” available around that time, namely the Shur-Hit;



    And the A&W Diverter, which apparently was what gave the devices their common name;


    The A&W came in 4-to-1 (shown) and 2-to-1 types, meaning a pattern 4X as wide as the height or one 2X as wide. The makers stated that it was possible to fire rifled slugs through the 2-to-1 diverter, but trying to fire a slug through the 4-to-1 was likely to blow it off the muzzle.

    Both were marketed to LEO back then, with the recommendation that they functioned best with No. 4 buckshot, were marginal with No. 1 or 00,and had little or no effect on No. 0 buck.

    What the designers apparently didn’t understand was that in police work, we’d rather a shotgun not generate wider horizontal dispersion of buckshot. That’s a pretty certain route to hitting an innocent bystander- or a hostage.

    What we wanted was the equivalent of an Extra Full choke that would deliver pretty much the entire load of buckshot almost like a slug, normally to the center of the target’s chest. The objective being to achieve the idealized “one-shot stop” about the only way it could be accomplished- namely by essentially pureeing the target’s vitals and “shutting him down” in an instant.

    The result, of course, was the Glaser Safety Slug and similar “pre-fragmented” projectiles for pistol and rifle ammunition.

    In my experience, the .357 Glaser and MagSafe worked better than either the .38 Special or .45 ACP (they were going faster), but the .223 Glaser never worked very well, tending to “blow up” just under the skin, leaving a relatively shallow but non-critical wound in muscle tissue and not reaching the vitals.



    • For a long time the FBi and other LE depts. went to slugs due to legal concerns over the spread of shot or an errant “fkyer pellet.” Many years ago the G-men abandoned shotguns alltogether, and just do “familliarization” training with the redoubtable old 870. Meanwhile, civilian tactical and defensive shotgunning exponents are touting the benefits of 8-pellet 00 buckshot with flight control (‘flite control’) wads from Federal for their very tight patterns from cylinder-bore shotguns and the absence of a ninth pellet “flyer.”

  8. Some early SOF units in Vietnam used these. Carried by the point man to break up ambushes.
    See my comment above about “Patches” Watson.

  9. The use of 6-9 mm buckshot is caused, almost exclusively, by the desire of the military to penetrate winter uniforms, items of equipment and other intermediate barriers at a distance of up to 100 yards.
    This is another dead end.
    Typical ranges for a shotgun are up to 50 meters. In fact, this is usually up to 30 meters or even closer.
    For such distances, a fraction of 3.5-4.5 mm works quite well on a person in clothes (and most urban animals).
    Such a projectile is guaranteed to hit the target (of course, if the target is at least partially covered by a dispersion spot). Such a projectile does not fly too far and does not penetrate through typical obstacles like light walls and so on. Even if the target is in front of a display glass behind which people are standing, they almost certainly won’t get hurt.
    Such a projectile provides an excellent stop effect, incomparable with the action of conventional pistol bullets.
    Finally, the affected object, if it can hide, will inevitably require surgical service to retrieve of the pellets.

    The only drawback is that the surgeon will not be happy with the extra work. 😉

    PS And attempts to use rifle bullets, coins and other nails in a shotgun shell are, if not insane misanthropy, then at least irrational. LOL

    • In the United States, shotguns have long been primarily police weapons. The U.S. and British militaries are unusual in having deployed shotguns in combat: U.S. Civil War, Indian Wars, WWI, WWII, and then in Vietnam. Primarily a niche weapon due to its limitations.

      A 00 buck pellet is approximately 8mm x 9. A No.1 buck pellet is 7.5mm x 16. No. 4 buckshot is 6mm x 27.

      As the somewhat grizzled old Gabriel Suárez once put it in his police-derived shotgun manual: “suited for close-range, short-duration conflicts that do not require a great deal of fire-power (i.e. rounds per target) or extreme penetration.”

      As the late Abbie Hoffman put it in “piece now”: “The shotgun is the ideal defensive weapon. It is perfect for the vamping band of pigs or hard-heads that tries to lynch you.”

      • “(…)U.S. Civil War, Indian Wars, WWI, WWII, and then in Vietnam.(…)”
        Wait, do you want to imply these weapon were not used in Korean War?

        • guarding prisoners maybe? I think the terrain augured against shotguns on the Korean peninsula. Then again, the late war before the armistice era was WWI with WWII weapons, no?

        • Truth be told, I think the vast majority of shotguns in WWI were used for guarding prisoners… And the most common use of shotguns in WWII was training aerial gunners for bomber crews. It is one thing to bust clay pigeons from a standing position, and quite another to do it from the back of a moving truck, to mimic that aboard a B17, B24, B25, etc. etc. both aircraft will be in (high speed) motion…

          • Of course naval boarding parties have long hewed to the blunderbuss and the scattergun too… Another specialized niche where the shotgun excels, even if it is not adequate for any number of other military roles.

  10. From American Rifleman – Looks like the message on #4 vs #00 got through…

    “The most common type of combat shotgun ammunition issued during the early stages of the Vietnam War was World War II-vintage “M19” shells. These were all-brass 12-ga. shells loaded with 00 buckshot. Although durable and water-resistant, much of the supply sent to Southeast Asia was poorly stored and a large amount had to be discarded due to corrosion.

    The standard sporting shotgun shells of the period had plastic cases that were also water-resistant and durable, and they were all but immune to corrosion. In addition to these positive attributes, they were much cheaper than the earlier all-brass variety. Plastic 00-buckshot ammunition was adopted by the U.S. military and initially given the designation “Shell, Shotgun, Plastic Case, 12 Gauge, No. 00 Buck, XM162.” The shells were typically packaged in 10-round cardboard boxes. Twelve 10-round boxes were packed in a metal ammunition can. The individual shells were standard 00-buckshot shells (red plastic cases) indistinguishable from sporting ammunition of the same variety.

    It was determined that smaller size shot, such as “No. 4 Buckshot,” would be better suited to certain types of combat situations than the standardized 00-buckshot. To this end, ammunition of this type was adopted as “Shell, Shotgun, Plastic Case, No. 4 Buck, Special, XM257.” Early versions of the XM257 shells were red plastic with the nomenclature stamped on the outside while later production shells were made of green “subdued” colored plastic. The XM257 No. 4 buckshot was packaged in the same type of 10-round boxes as the XM 162 No. 00 buckshot, and both types of No. 4s were used more or less concurrently from the time of adoption through at least the early 1990s.

    • Thanks for that. The British in the Malaya COIN experimented with having a buckshot load that contained two different sizes of buckshot, but in the end settled on regular “SG/LG” 00 buck with 9 pellets from the Browning Auto-5 and 870. The shells they used had paper hulls, which I though must have been a disaster given the humid, dank, moist jungle environment, but people who know how some of these shells were made and waterproofed back then have asserted to me that I don’t know what I’m talking about and that there was a solution to the problem… Jury’s still out, I guess.

      I’ve seen green/ OD 00 buckshot shells intended for military use of the munitions. Of course, after very many disasters of people using the wrong gauge of ammunition in shotguns, most manufacturers have adopted yellow hulls for 20-gauge, and purple hulls for 16-ga. There are a host of colors and even transluscent plastic hulls for 12-gauge ammunition, however. Remington loves green, Winchester opts for red, Hornady will mix it up with a black hull, so then Remington will do so as well… Presumably marketing and advertising. Sometimes the markings on the exterior of the shell become difficult to read or worn off too.

      Recall that in past discussions on shotgun-related Forgotten Weapons posts there flechette shotgun rounds, as well as the navy’s “silent shot-shell” that was a telescoping shell that contained the noise, smoke, blast, etc. inside a piston/shotshell. It threw a small load of No.4 buck pellets. I’ll have to see if any of those cartridges were used by a “duck-bill spreader choke” Ithaca 37?

      Also, the “Liberator” four-barreled 16-ga. or 20-ga. project, which our intrepid Ian M’Collum sleuthed out at the Cody Firearms museum during one of his research trips there… Eventually the idea grew into a ponderous 12-ga. design that was marketed to law enforcement, without success.

    • I have not seen this article.
      All from personal experience.

      To hit an object, it is much more effective to make many small holes in it than to try to make one or two larger ones, but with a good chance of either missing at all, or hitting an insignificant place or into a buckle, a magazine or whatever.

      It doesn’t matter what size the buckshot is, it does not penetrate any noticeable metal barrier. Even the “foil” English helmet of the WW1.

  11. Ian, really? 2 shots per target, w/o sights, and you’re trying to derive data? Interesting premise, not worth my time to watch once I figgered out how you’d garbled it.

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