Why Don’t We Have Top-Loading Shotguns?

When I posted some video of the real-life Halo M90 shotgun, one of the most common questions I got was, “why don’t we have top-loading shotguns like that?” Well, it’s an intriguing question…so let’s see if we can find the answer.


    • No point to top load a magazine, its plenty easy to bottom load and you don’t have a bunch of weight high up throwing off balance and obstructing view.

  1. to Ian, I have a century arms 45/70 pistol if you want to shoot it next time your in the Cheyenne Wyoming area

    • And if Ian is in Cheyenne, he needs to go over to Chadron, Nebraska to the Museum of the Fur Trade to see their firearms collection. HINT: the museum has French rifles that were part of the fur trade.

  2. I suggested top loaded shotguns for competition use to an Army friend last summer based on some reload drills I saw Lena and Jerry Miculek using, and we were both wondering why no one had made any, especially since you can help the recoil with a bottom placed barrel

      • In space no one can rain on your magazine port …

        Though once you board a spacecraft with artificial gravity you’ll have to watch for spiderwebs and dust …

    • And, dirt. Along with everything else, to include your clothes. Gravity is a bitch; you don’t see too many shirttails going into bottom-feed magazines, but I bet you good money you’d see all sorts of that with top-mounts…

  3. Another benefit of a top loader could be the gravity on the shell during the cycling of the action. It would seem like the shell would drop into the correct position much easier than being forced up.
    Seems funny that John Moses didn’t come up with it.

    • that’s a disadvantage. You want the shell to stay on the shell lifter, not freely fall into the action, and possibly jam up or jump out of the ejection port.

      • I think that you’d have to figure out some sort of fully controlled-feed system for a top-mount magazine.

        Another consideration that I just realized today was that Halo sort of presumes that everything is zero-G rated; how, exactly, would that affect your magazine design considerations?

        • I would say that in zero-G environments, the feed system would have to be like a box magazine to force the next round into position. No gravity to help make the shooter’s actions workable. Look at the videos of astronauts trying to do work in zero-G. They fumble around a lot.

          • As I said… You’d want something controlled-feed. You could do it with a tube, but a magazine would probably be easier…

            I seem to remember that there was once a shotgun out there that had a purely mechanical (no springs…) tube feed. There were little fingers around the cartridge rim that ratcheted with the pump action… I can’t remember where the hell I saw it, but I clearly remember going “Well, that’s a thing… I wonder why someone thought this was a good idea…?”

            Probably had something to do with getting around some patents, or something similar…

          • Yeah, I don’t think it got very far.

            It is an idea, though… Part of the problem when you’re thinking about these hypothetical/fictional weapons “Of the FUTURE!!!!” is that we just don’t know what we don’t know about that environment. It’s entirely possible that there are some very basic things about long-term exposure to vacuum and zero-G that we’re only going to learn the hard way, and the design of the weapons will have to be adjusted to compensate.

            I wish I could remember where the hell I saw that weird-ass shotgun feed. It was only for about three rounds, and I can’t remember if it was just drawings or someone had made an actual working model. The way it worked was kinda slick, but I can see where you’d have some serious kinks to work out. If you picture kind of a longitudinal belt feed, you’d sorta get the idea of what it looked like.

            It’s weird the way I can almost visualize the material I found it on, but I can’t remember where or when I saw it. I want to say it was one of those seriously old-school annuals that the gun trade used to put out, and it was about a two- or three-page write-up. It was either some weird-ass European country where it was from, or a European expat living here in the US.

            Like as not, it may be my memory conflating a couple of different things I saw, and when I was thinking about how you’d do a controlled-feed tube magazine, it just combined vaguely remembered and entirely disconnected things from years ago… I could swear I saw something like that, though.

          • Gravity causes wear and stress on material. Without gravity, would firearms need to be so robust? Would lubrication be less important. But will a vacuum cause other damage to material?

            What will be the performance of propellants in a vacuum? They need oxygen to ignite. Would a vacuum suck the oxygen out of cartridges? Would better sealed cartridges need to be invented? Would oxidants need to be added to the propellant? Would the propellants continue to ignite in the barrel, to provide more velocity? Would rifling still be needed? Would bullets have to still be pointed, as this is done to help overcome air resistance?

            Seems like some interesting research could be done on the topic. Anybody willing to find a venue to discuss these matters and maybe find a way to test the issues involved?

            As far as your memory — I torment myself with trying to remember where a saw/read things. At the time what I encountered was interesting, but did not seem important enough to document where I found it. Later on, when the matter is important, I kick myself for not knowing where I found it.

            We live and learn. Then we grow old and forget it all.

          • @Bart,

            Propellant already has its oxidizer built right in… Standard stuff works just fine without atmospheric oxygen needing to be piped in. If you stop and think about it, how much air is in a cartridge…? Oxidizer has to be in there, already.

            The memory thing is something that I really wish someone would freaking address, already. It drives me nuts that they don’t have some application you can use as a life-long aide memoire, that you could insert running notes into when you run into something you might need later on… And, why don’t they teach kids how to manage things like that in school? I swear to God, the useless crap they pumped into my head, and never once did anyone bother to provide any kind of “working theory of knowledge”, or how to go about developing such a thing.

            Were it me, I think that’s a critical thing that should be taught: How to learn, how to catalog what you learn for later use, and all the rest. You don’t know the number of times I’ve had to go looking for something I know I once knew, but I have lost it because it didn’t “stick” in long-term memory. Plus that, there’s the issue of professional stuff… I had an acquaintance I used to work for, an engineer. He had this entire collection of carefully annotated references that he cataloged and carried with him to every single job, and it was an education just to watch him work with that stuff. He still had some of his original references and textbooks from college, filled with a thousand and one margin notes…

            I’ve got a copy of a book he culled when he didn’t think he’d need it any more, and I’m here to tell you, the damn notes are worth more than the book.

            You have to wonder what efficiencies and what brilliant ideas have been lost because someone forgot something, and had no way of recovering that memory. And, when nearly everyone is wandering around with a smart phone the way we are today? WTF? Why isn’t there an app for this?

            Seems like it should be a damn utility built into the OS, really. I’ve been wondering why nobody has ever done this sort of thing on a computer, even… Seems a weird oversight, ya know?

  4. How about the Neostead or the Russian rmb-93? Both imo seem like they’d be slower to load than a standard tube but it is on top …

  5. might be a very good point.
    Consider the shells at the time were paper. Feed from below and they stay dry, most likely. Feed from the top and water could trickle down into the action, swelling the cartridges.

    Not the only possibility, but a consideration.

  6. What about sitting in a duck blind in the rain with water running directly into the reloading port and onto whatever mechanism is below?

  7. From memory, and so not a certain reference, but I think Fairbairn wrote that in the 619 gunfights he saw in Shanghai, nobody ever reloaded.

    • The lack of needing reloads is one reason that the difficulties of reloading a cap-and-ball revolver were not an issue. In most civilian uses for such, the matter was settled in six shots or less.

    • That was then, this is now…

      Today’s combat techniques are predicated upon mass of firepower that necessitates being able to perform rapid reloading and clearance drills. If you are unable to perform, no worries: You’ll soon be a casualty.

      Fairbairn was dealing with a milieu that did not have things like the AK-47 or AR-15, light handy carbines capable of full auto. If he had, I suspect he’d have had a different opinion on the matter.

  8. One overlooked drawback of the Spencer/Bannerman pump is that every time you rack the action, the carrier flips up through that upper port right into your line of sight. (Yes, I have fired one.)

    The Pedersen .276 military rifle prototype of the 1930s, with its toggle action, flips the toggle up into the shooter’s line of sight with every shot.

    It just could be that shooters don’t cotton to having their sight picture blocked at every shot, even for a fraction of a second.

    And before anyone says “Luger”, remember that the Parabellum redesign of the unwieldy Borchardt was intended to make it more amenable to the classic “one-hand” shooting stance of a century ago. In other words, it was designed for instinctive point shooting, in which you aren’t necessarily even looking at the sights.

    And even today, the Parabellum is still one of the best-designed pistols for point shooting, in terms of ergonomics. Only the Ruger and Whitney .22 self-loaders really come close to it in that area. All three are natural “pointers” in point shooting.

    A shotgun needs to be a natural “pointer”, no matter what you are using it for. Just as a dangerous-game rifle needs the same attribute.

    A thing like the “Halo 90” shotgun, or any of the box-magazine shotguns, seem to have problems in that department. And that’s even allowing for the number of box-magazine shotguns based on AR architecture.

    The main drawback of the box-magazine shotgun is of course the rimmed shotgun shell. Loading a box magazine with 12-gauge rounds is exactly like loading an SMLE or No. 4 magazine with 0.303in, or even more like loading a Bren magazine. Get one rim in back of the rim of the round you just loaded before it, and you’ve stonewalled the entire production.

    The answer is of course a true rimless or at least semi-rimmed shotgun shell, which the U.S. Navy experimented with in the 1960s. The main problem was that it only really worked with full-length brass shells (see Chinn, vol. 5). Today, we have polymers that are probably tough enough to make a rimless 12-gauge round that won’t come apart during extraction in autofire, but I’d really want that seriously validated before greenlighting it for IOC.

    More to the point, exactly why do we need or even want such a shotgun? If someone wants greater firepower in a shotgun, the KelTec KSG, with twin 7-round tubular magazines, seems to offer everything required in that area in a compact package made to order for either “game-playing” or what we always referred to as “serious social intercourse”. (The latter defined as “Somebody is going to get f**ked up- make sure that it isn’t you“.)

    We tend to forget that firearms design, like a lot of other things (coffeepots, washing machines, etc.) evolved the way they did because that was what worked.

    Even today, the underbarrel tubular-magazine setup is still one of the best for dealing with rimmed cartridges in a repeating weapon.

    And yes, if I ever found a Mossberg 46M-B .22 bolt-action with the tubular magazine for a decent price, I’d grab it, even today.

    clear ether


      • The Navy found that due to the different stresses set up in a brass “battery cup” case-head in making it rimless, the high pull factor of automatic actions tended to cause either rim pull-through or case-head separation.

        Also, when the chamber heated up, there was tendency for the “battery cup” to pull right off the plastic case, which had literally been softened by the residual heat from previous rounds. Sometimes the plastic would fail just in front of the brass “cup”, leaving a gooey mess stuck in the chamber.

        Hence the use of full-length brass cartridge cases, which was definitely not what the Navy wanted, for reasons of expense.

        As I said, the problems can probably be solved by the use of more advanced (and heat-resistant) polymers today. Such as those in the new types of plastic-cased rifle ammunition with a “snap-in” brass or steel case head to hold the primer and allow extraction.

        Which brings us to the interesting question of which experiences higher stress loads in extraction; a rifle cartridge like 5.56 x 45mm or 7.62 x 51mm, or a 12-gauge 3″ magnum shotgun shell?

        For that matter, do we even know how much force (in terms of Gs- earth gravities) each one experiences in extraction?

        The more we learn of the technologies involved, the more we realize that certain very basic questions about the physics involved have apparently never actually been asked.



        • They could probably make it succeed with common polymer if they just don’t induce stresses in making it rimless?

          The stresses involved in punching out the crimp must be enormous. Extraction (a parallel plastic tube sliding out of a smooth chamber at very low pressure)?

          • The case-head would still be metal.


            The extraction problem is residual heat. The kind of heat that can cause “cookoff” in a full-auto weapon firing from a closed bolt. (Heckler & Koch HK-53 is one of the more obvious examples.)

            That level of heat can melt or at least distort plastic shotgun shell casing material. And there goes your “parallel plastic tube sliding out of a smooth chamber”. More like salt-water taffy coming out of the cooker.

            Check out the Atomic Rockets website;


            The “rocket guys” long ago figured out something gun and ammunition designers are still not quite getting. Namely, that waste heat has to go somewhere.

            And if you can’t radiate it off or otherwise dispose of it fast enough, it’s going to stick around and cause problems.



          • Ian was talking about conventional semiauto shotguns (which cycle normal plastic shells all the time with no such issues), and I read your comment / typed my reply in that context. That has everything to do with burning a relatively small powder charge in a big open tube at a low rate of fire – which of course would change in an MG. While I have no reason to doubt you or COL Chinn that that manufacturing in that one instance created stresses, the difference in general has nothing to do with the presence or absence of a rim.

          • Eon,
            All-brass 12G shells are certainly expensive, but I always thought available, affordable, ’06 Basic brass could be an excellent basis for an AR10-compatible shotshell for all the roles you cited in your response to Kirk. I wish we had an edit button.

        • It would need some sort of material that doesn’t soften with temperature and it’s not as expensive as metal, like, for example, paper.
          Obviously paper ignites around 240 c°, but smokeless powders generally ignite, and polymers melt, before that.
          You can also plastic line it internally, for better protection of the powder.

          • The problem with paper is that when subjected to G forces in this range it tends to crumple. That’s why we stopped using it for shotgun shell casings to begin with, along with its environmental sensitivity. (Swelling up and softening when wet, etc.)

            Unless there is a polymer case material with most if not all of the attributes of actual cartridge brass (or at least mild steel), you’re going to have problems with anything other than a full-length metal cartridge case. Shotguns are not nearly as tolerant of less-than-perfect case design and construction as most people think.

            Ask any professional skeet or trap shooter. They know.

            clear ether


          • Paper is obviously sensible to elements, but simply storing it in plastic would help a lot. It’s not like armies never used paper cartridges.
            Paper shotshells were used in WWI. The problem they had was that they were waxed paper, and the wax, once partially melted if inserted in a hot barrel, could freeze there when the barrel got cold.
            As for the G-force, I’m not persuaded. Shotgun actions don’t cycle THAT fast.

      • Then you get into the whole debate of drums vs. boxes. Would three 10 round boxes, connected to each other provide fast enough reloads to be worth the savings in weight from a drum?

    • “(…)have polymers that are probably tough enough to make a rimless 12-gauge round that won’t come apart during extraction in autofire(…)”
      There exist Intrepid RAS-12 / AR-12 https://modernfirearms.net/en/shotguns/u-s-a-shotguns/intrepid-ras-12-ar-12-eng/ consuming polymer-case ammunition, strictly speaking it is rebated rim, not rimless, but anyway that prevent problems of conflicts of rims inside box magazine. It is self-loading, but I do not know if it simply due to intended customers only or intended customers and technical problems in case of full-auto.

  9. So long as you’re limiting yourself to inert projectiles, I don’t think the shotgun is ever going to supplant rifles. Not enough “bang” for the weight, insufficient range, and a generally limited use case. If you’re carrying a full-auto carbine, you can do the shotgun mission from muzzle out to around 400m; with a shotgun? Nope; not going to work. And, since the general attitude and fact of life is that if you’ve allowed the enemy into the range fan for a shotgun, you done f*cked up, boy…

    Specialist weapon for special cases. That’s all the standard shotgun will ever be, I am afraid.

    • The whole point of the police “cruiser shotgun” has always been up-close, right-now stopping power with limited danger space.

      In police work, we’re not supposed to injure or kill law-abiding citizens who might be on the far side of a valid target.

      The shotgun loaded with buckshot (maximum effective range about 30 yards) or slug loads (MER about 70 yards) did this very consistently. The latter were also very effective at stopping vehicles, especially ones trying to run roadblocks.

      Rifles in police work always had limited utility precisely because they could “shoot through” a perp, and hit somebody a block or two downrange, even through structural materials (walls).

      The M1 Carbine in .30 USC was a favorite “police rifle” for generations precisely because when loaded with 110-grain JSPs that duplicated the ballistics of military FMJ ball, it had high stopping power at close to medium ranges with much less potential for overpenetration than most other rifles around. (In West Germany in the 1970s, specially set-up, scoped Carbines were used by police sharpshooters, including GSG-9’s, for this exact reason.)

      The trendy change to the HK MP5 in 9 x 19mm caused some problems in this area, due to the overpenetrative tendencies of the 147-grain subsonic JHP load. Agencies which stuck with 115-grain JHP at 1,200 F/S didn’t have that sort of problem.

      The final answer for police tactical teams seems to have been the M4 in 5.56 x 45mm loaded with 55 to 60-grain JHP. Combining high wounding capability with not being overpenetrative.

      Another example of a specialist weapon for specialist cases.



      • If you want to stop a vehicle, check out the insane shotgun slugs on YouTube on the taofledermaus channel.

      • 00 Buck is still deadly past 30 yards, it just is not accurate. Rifled Sights shotguns can hit a man-sized target at 100 Yards. 15 years as a LEO Instructor, and I have done that.

        • So have I, but “maximum range” and “maximum effective range” are two different things.

          And there’s a difference between an instructor who may shoot all day, every day for weeks on end, and a peace officer who (1) only fires his weapon maybe once or twice a year for qualification and (2) spends most of his practice time (if any) concentrating on his marksmanship (if any) with his sidearm, rather than the “patrol shotgun”.

          As an instructor myself, I learned that 00 buckshot (still the most common load in police work) begins to open its pattern at 20-25 yards to the point that by 30-35, out of nine pellets maybe three or four will hit a silhouette target in the kill zone(s). That should be enough, as each pellet is basically a .32 caliber lead bullet, but you’re not getting the full effect of the nine-pellet cluster beyond 25.

          As for slug loads, certainly a Foster slug out of an IC 20″ barrel with rifle sights (properly dialed in) will group inside eight to ten inches at 100 (BTDT), but back down at 65-70 yards it’s more like half that; four to five inches. Meaning, your chances of a first-shot hit are about twice as good if you don’t push it beyond 70.

          I always taught “Use your sidearm out to 25 yards, use the shotgun out to 25 yards with buckshot or 50 yards with slug load, beyond that use a rifle.” Most agencies I trained officers (and sheriff’s deputies) for used .30 M1 Carbines or Colt Sporter .223s, although at least a few old-line ones stuck to Winchester 94s in .30-30 WCF.

          Considering that a 150-grain Silvertip from a .30-30 will more than adequately hit and take down a buck deer at 150, which means it would do likewise to a man at the same range, it was sort of hard to argue against them. Especially because I used a ’94 quite a bit myself back then.



          • A point to remember with all of this is the sheer psychological impact of the weapon itself.

            Somehow, a rifle or pistol wound is less intimidating to a lot of folks because “one small hole”, I suppose. The same guy, presented with a shotgun, has templated that weapon on delivering a much more damaging wound. An awful lot of laymen picture a cartoon-like hole resulting from a shotgun blast, one you could see clear through them… Which is why you’ll often get more compliance as a cop-with-shotgun than one with “just” a rifle or pistol.

            I blame the media. And, Saturday-morning cartoons…

  10. You have to take into account the range at which you can hurt someone. This is to protect Grandma Moses from getting shot leaving the Stop and Rob down the street. And with slug rounds and the Remington’s we had with Rifle Sights, it did not take a lot of training to hit a man-sized target at 50 yards. The Ranger, Joaquin Jackson, was used as a model for EXTREME PREJUDICE Nick Nolte’s character. He DID carry a 30-30 under his seat. Yes, I worked with him in the 80s.

  11. I thought of something. Would conventional firearms even be practical in a zero-G vacuum? I do wonder if convention cartridges would even ignite under such conditions.

    But a more fundamental problem is Newton’s Third Law. The recoil from a conventional firearm would propel the shooter backwards. There would be no gravity to keep the shooter from being moved and there would be nothing to stop that movement. So maybe the whole HALO rap is just silly.

    But there is an alternative that I think would solve all problems:

      • I always thought the obsession with only energy weapons on Star Trek would not be realistic if that universe was real. The “shields” blocked energy weapons, but not solid objects. So why not a mix of energy and projectile weapons?

        But I would think an energy weapon, of some sort, would be what an individual. out there floating around in space, would need. Though a no-recoil projectile weapon, like GyroJet might also work.

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