When someone starts to ask "Why?" in relation to firearms the answer is almost invariably "Dirt." one way or another.

they'd be too op against the flood

Bro in my book "It's fucking cool" does most of the heavy lifting.

The most obvious reason on the top of my head are : 1-Rain and dirt can fall in the action, if a cover is added then it makes the reloading slow again. 2-Not being able to top load while aiming and being ready to shot at the same time, this is a deal breaker in my opinion. Then if it is a pump action then I would also add: 3-Overall heavier because of added structure to make the pump action works far away from the tube. 4-Pump grip being too close to potential hot barrel, a heat shield seems hard to incorporate with the pumping action.

Kel-Tec will probably be the first company to make one

Even as a young kid watching the reload animation in the first Halo game I was like "Wow that makes a lot of sense. Why don't they do it that way?" Now watching competition shooters and seeing the bizarre contortions they go through to speed load a traditional shotgun, I still think "Wow that Halo shotgun still makes a lot of sense. Why don't we do it that way?"

As demonstrated in The Library, the m90 proved itself effective during a severe flood outbreak. With is exceptional stopping power it tends to dismember flood combat forms with ease and I’m sure if you ask S117 the top load function is likely a non issue.

It's weirdly refreshing to have an explanation be 'no reason, that's just how it happened to be'

TELL THAT TO THE COVENANT!

In competition shotgun shooting, I believe its relatively common to invert the gun to have easier access when inserting the shells, so I think there would be some real merit in not needing to do that.

There is РМБ-93 "lynx" shotgun and her big brother GM-94(same thing but 43mm grenades) they loads from top, and also have cool design with moving barrel

Hunting-culling wild hogs is a situation where this might be useful. Scary stuff can happen with them, can easily leave the hunter in mortal danger.

In the context of Halo, the CAWS is canonically an 8 gauge shotgun. Magazines for 12 gauge semi auto shotguns generally tend to be more clunky or bulky compared to say, an AR or AK magazine. Now think about a mag that has to hold 8 gauge shells, not 12 gauge, and suddenly a t00b makes a bit more sense. The CAWS is also very obviously the go-to solution for incomprehensibly horrifying parasites and energy sword wielding invisible space lizards.

For shotguns with a specific use like trap shooting, yeah that'd be neat. However, as a duck hunter I can tell you those foggy mornings can be extremely damp and even rainy, and I just don't like the idea of my action slowly filling with water as I wait.

Concept: Like the M14 with a detachable magazine and top loading capable. Like the SPAS-12 with semi-auto and pump. 1. Top loading shotgun with a tube above the barrel that works on pump action with a detachable magazine that works on both semi and pump. 2. A 5 position selector switch that rotates or slides through Safe, Semi, Pump Mag, Pump Tube, Safe would be sufficient. You could get away with 4 position and leave off the second Safe. I personally like the tang safety on Mossberg's. A quick glance tells you which of the 5 positions you are set to. An AR style rotating selector is also doable. Application: MILITARY 1, You almost always have more ammunition than magazines. Carrying a few extra loose shells is not a big deal. 2. You could load the tube and a mag before heading off base. Breaching rounds in the tube and combat rounds in mag. 3. The brass of the shells can be color coded so you can identify what type of shell is next in the tube. At most, a slight shift of the head or gun would let you see the end of the tube. Drawback: This would be a complicated, expensive, and heavy gun

Growing up on a farm in the UK we had the usual double barrel 12 guages, except me who had (and I can't recall the make alas) a Greener EG Mark III style top loading single shot lever action 12 gauge. Overall it was a fantastic hunting weapon so long as you didn't need a second shot immediately - given most of my generation didn't have auto eject on their guns, using my under lever I could in fact get a better rate of fire with the lever flinging the cartridge out. Nighttime shooting when it was difficult to see where to lead, and on a bouncing truck bed and this was the gun of choice. Thanks for the distant memories!

If the incentive to load shotguns faster developed before the box mag, I think there’s a decent chance we would have seen top loaders. Interesting alternative history.

John Browning's first repeating shotgun design, the Winchester 1887, was a top feed, bottom tube magazine.

top feed on a pump action is partly due to flex physics of making the pump arm go further off of it's centerline, similar to how a pistol grip on the pump grip causes angled stresses. On a semi-auto like the bernelli in theory it should work just fine, but added into the familiarization, ergenomics, and 'if iit ain't broke, don't fix it"

I would agree that the height over bore is the main reason against. Additionally the advantages of having a top load is mute with many speed loading techniques involving rotating the gun into your armpit to move the loading gate dorsally

We have one, but not in America, RMB-93 is top-loaded. Also pump-forward, and double-action, it's a stack of oddballs.

The only thing I can think of would be the opening for reloading being more likely to get clogged with dirt since it is on top. When it is open to the ground stuff falls out of it, it does not "pool" inside of it.

That is really interesting. I had always figured it was so you could keep the weapon raised on target, and load shells, but then trying this out, it is very difficult to support the weight of the shotgun and push rounds in, so then I figured it was just mechanically more simple and site over bore height.

This is my first time seeing this channel and this is my first video. As an avid Floridian gun enthusiast. I'm so glad to be here now!! Thank you.

Gun Jesus has, once again, made my morning at work less boring

The solution is obvious, five 8 round tubes surrounding the barrel in a star pattern with forward ejecting spent shells in case you missed with your 40 + 1 street howitzer

most people who would use a "Combat" Shotgun now probably use a big drum magazine maybe a box magazine ... but i still would love to see more top loading shotguns they are just cool even if they are just a novelty item for most people at the moment ...

Thx Ian... Recalling, Some WWII Trench Guns were top ejection, bottom feed... (Win Mod 97) The Box feed point is well taken. But a Top Feed Tube seems less likely to be banned.

I can't blame anyone for forgetting the flash-in-the-pan that was the ill-fated Utas UTS-15, which was not just a shotgun with the magazine on top. It was also a dual-tube, bullpup shotgun. The Kel-Tec KSG-12 flipped upside-down. It used a lot of polymer and was a Turkish piece of junk in the end, but there's your production, top-fed shotgun.

Bear in mind. The Halo M90 Shotgun in Halo CE was something like a **6 Gauge** and most of the ones since 2 have been at least a 8 Gauge. The size of the shot-shells alone for the one in CE would result in bulky and decidedly unhelpful difficulty in storing said mags and even loading when you got a squad of Elites yelling "Wort-Wort-Wort" about 10 yards away, even more so if your trying to somehow shove said bulky extra large mag into the gun and the lead Elite has an Energy Sword. Within the context of the Game Universe's lore, the top feed tube makes quite a good amount of since. Purely from the stand put that were dealing with shell sizes and outright firepower to boot that render the idea of mag feeding difficult, and that's before you account for the fact that if a Marine or heaven forbid an ODST is in a situation were said Shotgun is being used, things have already likely gone far enough pear shaped that the last thing they need is to be fumbling with a mag that takes up literally half of their armor's ammo storage. However within the context of our universe it is a little confusing why Top Feed never became a thing, until you remember that 12 Gauge while bulky can still be shoved into a mag and it be perfectly serviceable and useable and is way faster, and holding anywhere from roughly 5 to 8 shells and still being short enough and small enough to easily carry and use, with 10+ shell count mags quickly reaching the point of being unusable outside of it being the starter mag or taking the piss at the range with your friends after a couple of beers.

Army vet here. In the infantry we had a couple of shotguns that we used for breaching that were side loaded. These tended to be shorter shotguns that we would use to blow the hinges off. A tiny flick of the wrist and you're loading it from the top while still aiming it where it's getting fired, the thing is that these are very short range weapons.

So one thing I could see that would be a issue with a “top loading” shotgun is weather and debris issues. I could imagine getting a lot more chances of dirt, sand, water, hail, etc. with the loading gate faced upward. If you’re in winter environment you’re just having water go straight into the mag tube which can and will freeze unless you somehow make a perfect seal and nothing can get in (would love to see a Garand thumb torture test of that). Same if let’s say you’re getting shelled at with explosions all around you, you’re going to get a lot of debris potentially landing in that loading gate. I think if maybe we’re talking like shorty breaching shotgun, or even like a “shockwave” type thing it could work well. Were you’re expecting maybe only a handful of bad guys in a room, but maybe you just need to top off super quickly if you run out. But you’re less likely to have to be in a prolonged fight. Which at that point you’re going to go for something with more accuracy, rate of fire and ammo capacity

Actually, we have at least 1 shotgun with magazine over a barrel. It's russian RMB-93/RM-96 "Рысь" ("Lynx") anti-pump action. To chamber the shell, you need to cycle the barrel forward-rear (breech is fixed). So, obviously, it was easier to put the barrel on bottom and put a handguard on it. "Рысь" have some advantages (it is short and light, due to anti-pump construction), but it is not the most fastest or most pleasant gun to shoot.

this is similar to how the QWERT keyboard layout is a vestigial design from old typewriter keyboards to prevent keys from jamming by putting common letter pairs that are typed together as far apart as possible. The bottom fed design in tube fed shotguns is essentially a vestigial design from the old lever guns that were tubefed, from which they trace their design roots from. So yes Ian, the answer is in front of you sort of, since the answer is, "well that's how these older guns were made and nobody seems to mind, let's just keep doing that".

folks have presented some valid points about toploader weapons(rain/dirt catcher, sight alignment, ammo size, etc.), so i'd like to posit a compromise between toploader and bottomloader: side load, with the spent shell port being out the bottom of the gun. with the side load, you don't run the risk of rain or dirt piling up as easily with the toploader, but you still get the convenience of a faster reload for competition speed shooting.

Thank you, that was informative. I'm not sure why I needed this info, but I still enjoyed it :)

One bad reason was +70 years back shells were most-often made of paper and top loading shotgun would let dirt/snow/rain-water just funnel directly in. One good reason today to make top loading shotgun is to have slightly less muzzle climb maybe??? Gonna need Ian to test that last one though. :D

I would have thought it was to prevent dirt/water from entering from the top

It was alluded to in the original, but not mentioned in this video: it requires more parts and redundancies to build a top loading pump shotgun. if youre counting pennies, needing an entire other tube for your pump to slide on, is material, and weight that will quickly add up when manufacturing and shipping at scale.

Impact Props (another video on Impact Props Live) did show off this build in their Living With Chief series. They have collaborated with others and built their own functional Halo weapons too.

At 71, I still get a grin from the questions and observation you show us. Good on you!

The reason I bought a shotgun was for 3-Gun. A few years ago, I shot skeet with a friend of mine who has an over/under shotgun and he kept loading just the bottom barrel when he only had to take a single shot. I asked him why that barrel and he said that it had a more inline recoil impulse, which controlled muzzle flip a little more. That got me wondering why nobody made a tube-fed shotgun with the magazine above the barrel. When I started telling people about this notion everyone just thought it was weird. Now there a video about it! The "just use a box magazine" argument ignores 3-Gun gear divisions; box mags are only allowed in Open division under USPSA or UML rules. Tac Ops has (at least until recently) been the most popular division, which mandates a tube-fed shotgun. The division that's just been introduced is Modified which also requires a tube. All that being said, you're spot-on when you point out that fast reloading of a shotgun is really, really important in 3-Gun and somewhere between a lot less important and irrelevant everywhere else, so I'm not sure that we'll see any radical developments in tube fed guns any time soon.

Neostead 2000 Dual-Tube Pump Shotgun, a title from another one of your videos. I remember distinctly it being top loading but you had to break it open so I'm assuming without having to do that since that takes time compared to just sliding it in.

My first thought was grime and dirt. I just had a pretty crazy hailstorm the other day. The thought of the action filling with rain, hail, dust, or any combination of those, while the gun is shouldered is legitimate. My other thought is target acquisition. Doing a tactical reload while moving down a hallway or guarding a door would suck if you had to place your hand in front of your face. Loading under the gun without taking your finger off the trigger or blocking sight lines would be a major hindrance. Shotguns are the best weapons best suited for a tactical reload, your gun can stay topped while always ready.

Design consideration for the infantryman: A top loader with the loading port looking the way it does today means a big area on the top of the gun that traps rainfall into the action and magazine. Not a huge concern for catastrophic failures, but it could mean water in the tube spoiling your ammunition. And for a long maintenance schedule, it's important to keep what could be a lot of moisture that didn't have to be there from being trapped in the gun for long time. Anytime you can make the top of a gun more likely to shed water away from the action, the better.

The only other argument I can think over for bottom mounted ammo tubes over top mounted is that it having it on the bottom allows the tube to double as a forestock to hold onto/brace the weapon. Having the tube on the top means this part would need to be added separately which could increase the weight/cost of the product, and the alternative of leaving it off and holding directly on to the barrel is probably not the most ideal situation.

I like the IWI Tavor TS12 Shotgun’s multi tube system. Each holds 5 for a total of 16 ( 1 in chamber). On top of the fact that the tri-tube system is replaceable like a clip. I’m obviously just talking about the tube system here. There are a good number of issues as well. I just really like the innovative tube system it has.

The cool factor is a big seller for me. I also feel like Kel-tec would be the ones to mass produce these. As a Halo player since 2001, I'd love to get my hands on an m90. Best shotgun in the franchise. (Halo CE and 2 if I remember correctly.)

This one was interesting. I like the fact it's basically a weird middle technology where it's slightly better than what is typically available, but if people care about that, they can jump to an option that's far better than manual loading leaving it in limbo. It is neat though, and it needs to happen for that reason alone!

Top-loading is decently common in weapons - provided they're crew served. Bren Gun/ZB-26: Loader grabs empty mag, places new one, slaps gunner who is still tracking targets to indicate loaded. MK-19/M2: Open top cover, position belt , close. 40mm Dual Bofors AA mount - loaders feed clips on the top, brass and holding clips fall out bottom. Conversely - you don't see shotguns operated by multiple people (yes, I know of punt guns, but I am trying to be somewhat reasonable) so making the action accessible to others isn't a priority.

As for which is the first intentionality designed assault rifle, this is beyond doubt Colonel Furrer’s 7.65x30mm intermediate cartridge M1921 prototype based on a conversion of a Furrer MPi 1919. The barrel is chambered for the steel Manipulierpatronen. Only one example is known and you’re welcome to film it when you next visit Malta.

I've been replaying the Halo series lately and this exact question came to me, then tonight I see this. Good vid.

The main issue with mag-fed shotguns is that they tend to get very bulky very quickly. I remember the first time I saw a Saiga, and I saw a MASSIVE magazine attached to it. I asked how many rounds it carried, and the store owner told me "ten". Ten shots for a magazine that was about twice as long as you would want it to be. Talk about cumbersome. I look at Mossbergs mag fed shotguns and the only "reasonably sized" magazines hold 5 rounds. They are shorter than Saiga mags, but they are still VERY bulky. Honestly, mag fed shotguns (in a traditional layout) haven't seen much use in the military (AFAIK) because they are so much bigger than a "traditional" shotgun. Why add a massive box to the underside of your shotgun when a mag tube already holds 5-8 shells? (There is a mag-fed breaching shotgun, but it is solely used as a breaching tool, and everyone I have spoken to about it that has experience with it says it's hot garbage.) Assuming the "M90" could be built to work just as well as something like a R870, I see it as a straight upgrade. Either use sights or have a mag tube the same length as the barrel and put the front sight post there. A semi auto M90 that worked as well as a Benelli M4 would also be a straight upgrade. The problem is that shotguns are kinda falling out of favor with the military, in general. The new trend seems to be going towards smaller, breaching specific shotguns or alternative breaching tools.

As someone who isn't experienced in firearms (the only one I've ever fired is the Ak5C) but _is_ quite knowledgeable in engineering, I would guess that's _probably_ the reason why top-mounted tube mags aren't common. All of the ways I can think of to make such a design pump-action or lever-action (or self-loaded with pump or lever charging handle) would require a few more parts with more complex shapes in the mechanism requiring tighter quality, so it'd be more expensive for not that much of a benefit.

I think your assessment is correct on why there are few top loading tube shotguns. If you need fast reloads, you can get a box mag fed shotgun and the top loader makes your height over bore for your sights an issue. I do strongly suspect quad loads would be really quick with that top loader though. I guess it might have an application in a competition that mandates tube fed shotguns.

6:50 It is that for me, instinctive shooting. When you point at something it is easier to point at something if you can see the pointer.

I'd add the following to Ian's argument. You hold guns from the bottom, so that was the obvious place to stick a tube mag, where you have more options to wiggle/toggle/pump/tap things. Shotgun rounds resist magazine feed design, so they stuck with tubes, and tubes like to be near the hands. You might note we don't have a lot of tube mags in stocks, either; I'd say it's another case of ease of manufacture but also it's a hell of a lot easier to fish a round/spring/screw from a tube near my hands than fishing from the depths of the stock. It's also a really efficient thing to do with a handguard. You might note that in the HALO piece, it STILL needs a handguard, and that's wasted space if it's not a secondary tube.

Never played Halo games much, but this is an interesting question I never considered. Among so many youtubers who just repost old content, copy and paste memes, and other useless content consumerism bs, your channel is a constant flow of refreshing actual informative content. Thank you for sharing your knowledge with the world Ian. You have my respect for trucking on for so long and dropping knowledge for me to learn from.

The first thing that came to mind was exposure to the elements. Gravity would help water and dirt settle in from the top, easier than the bottom, and that would be bothersome, especially with the shotguns used in trench warfare.

When I read 'top-loading shotgun' my first thought involved something like a Bren mag. Thanks for a great video.

Halo really popularized top-loading shotguns. Honestly, it'd be cool to see this design done in real life. Halo shotguns in real life would be so awesome if mass produced. Bonus points if it's chambered in 8 Guage.

There is one top loader shotgun I can think of, the Winchester 1887. Of course the tube is still under the barrel and loading seems like it's a pain in the neck. I'm guessing when he designed the 1893 pump, John Browning decided it was better to move the loading port to the bottom than move the tube to the top.

I think the UNSC was able to get around the instinctive aiming deal with their helmet aiming sweet with the HUD on the glasses and eye piece

Top loading allows for ejection from the bottom more easily allowing it to be used as ambidextrous without the worry of getting hit by brass

I think a reason box mags wouldn’t work as well in Halo is because it’s 8 gauge. Those would be massive magazines. And I bet in-universe it being a pump (some models are pump-semi like a Spaz-12 or Benelli M3) would be the utility of different rounds of varying pressure from tear gas to armor piercing slugs. It is used for purposes like law enforcement and while inside a space ship after all. Plus, having the most rugged reliable gun possible would be good when on alien planets sometimes months away from help.

The tube can be used as the base for the handguard, especially pump action. So there is no need for a heat shield for the barrel reducing overall wait. You can see that on the m90 in the video it has three tubes instead of the more covenantal two.

with some kind of sliding cover over the feed port, you could probably mitigate the dirt issue a good bit, think AK/Galil. Idk there's probably some way to work around it, but not an actual demand to do so, so Kel-Tec probably would

The Inkunzi Neopup is the only top loader I can think of. The lebel also technically fits the description since its tube fed.

To be honest I figured one of the answers would be "having the loading port on top would make it easier for dirt and debris to get in the action", either by gravity or by being pushed in during loading. If the loading port is on the bottom, debris would tend to fall on the ground.

The russian RMb-93 comes to mind when it comes to real life examples of top mounted tube (and probably top loading) shotguns.

The obvious thing is that nothing is ever going to fall UP into the lifter when it's on the bottom. Out in the field, stuff falls on you sometimes. Put a skeletonized follower up there like a mossberg and a squirrel WILL throw stuff in there, even past the half court mark.

I think a big factor is if you're keeping your eyes on a target and have to reload you don't block line of sight by reloading from underneath. If you were to load from the top your line of sight while aiming down sights would get blocked by your hand

I think you're absolutely correct. I could see one reason for top reload: consider using a shotgun in a prolonged gun fight. 1) you do want to reload as quickly as possible 2) you do not have a set course of fire (as you do in a match), so you want to top up as opposed to run dry and reload a whole magazine It's not a very compelling reason in practice. On the other hand, making a top-loading shotgun can be a product differentiator anyway. Just for the cool factor alone.

I do think there is one more reason to not put the barrel under the magazine tube (specifically on a military style shotgun that's going to be fired a lot in rapid succession): Barrels get hot. Magazine tubes provide a natural buffer that helps prevent a shooter's hands from getting burned by a hot barrel, even if you miss the grip or your hand slips. WWI would have been a FANTASTIC opportunity to have an "upside down" shotgun for trench sweeping, since keeping eyes downrange and the action from getting dirty are important factors. However, that still goes back to barrels getting hot from firing them a lot.

Quick loading (preferably non-existent belt-fed) shotgun is ideal for drone defence shooting. "point defence" based mostly on spread of the lead in the air, instead of precision.

My first thoughts on top loading shotgun problems would be the sights, while you get a great view of your hands while reloading you lose view/focus of everything else, a slower to transition back to firing stance, I'd imagine a bit more complicated and bulky to have the pump below the barrel and the tube above, and the "easier" reloading can be eliminated with a nominal amount of practice.

One of the possible benefits I think off would be it would be easier to have the shells eject out the bottom like the Ithica 37 and make it more friendly to left hand shooters without needing some sort of conversion.

I figured the Halo shotgun was top-loaded because of it being used in power armor. No idea if that's canon, but it made sense to me

Tube mags still have their place. I can carry different kinds of shells, and in a pinch, quickly swap one out for a breaching shot or dragon breath or beanbag round as and when I need it, without having to change out an entire magazine, which itself is pre-loaded and I might not have on with what I need in it.

The only thing I can think of is that if you put an aftermarket optic on top, it could get in the way or make it difficult to load from the top

I agree with almost everything you said except for the supposed downside of worse ‘instinctive shooting’ if the tube is above the barrel. Since most shooters actually tend to miss high when they’re off, many competitive shotgunners actually use an extremely elevated sight rail multiple inches over the barrel. I used to be a consistent 23/25 in trap and always shot the low barrel of my O/U for the same reason. Whether you prefer the elevated sight rail or not, a shooter will get the feel of where and how they’re missing and will subconsciously adjust their aim point. Even then, as you’re shooting a pattern and not driving a tack, being a tube diameter low on your target is pretty unlikely to alter the outcome of the shot anyways.

In a combat/rapid reload situation, it feels awkward to feed shells in from the top if you're attempting to maintain the shotgun high and ready. You break your sight picture with your hand, have to reach further, feel like you need to lower the gun, etc. Sliding shells in from the bottom maintains your feed hand closer to a ready position, and doesn't interfere with your view. Now, this could just be an artifact of what we're used to, and it could work quite well either way. We all tend to have a bias for how we learned and have repeated. Great video, and a nice prototype Halo shotgun!

Since shotguns in military and police use are mostly for breeching and specialty purposes I think the visual aspect of the top loader would be helpful in special type ammo use. Especially is you could quickly rack the slide to check ammo type without the risk of discharging unspent rounds into the ground.

You missed the concept of 'topping up', that is an advantage of the tube magazine guns over box mags.

I appreciate the point of the practical rarity of speed reloading outside the competition realm. In all the police body-cam footage I've seen, I have never seen a long gun (shotgun or AR) be reloaded during a fight. The gunfight is always over in seconds within the duration of the magazine (be it tube or box). Even in military combat footage, I've never seen any speed reloads. While the rest of the unit is still firing, a soldier with an empty rifle gets behind the cover they were using, fumbles to get the magazine out, nearly misses the magazine well, and slams the magazine into the gun pretty inefficiently compared to competition shooters

how about a angled from the top fed tube, approx 45 degrees allowing your to cant the shotgun slightly, this would retain sight picture while reloading and not sacrificing instinctive shooting. i think that would be best of both worlds

Top-seed Shotgun, from engineering point of view, resembling several problems. Lower barrel brings heat closer to front hand, requires heavier hndgard. Shell feeding would be passive, less controlled than the "active" lifter mechanism. The hammer/trigger linkage would be more complicated (and longer) adding more cost for less "crisp" action. And more... Upper feeding port is more receptive to dirt and soil... In a shell: if it works...

Reloading from the bottom seems a lot more comfortable when I have the weapon shouldered or holding it otherwise. It would be kind of awkward to reach over the top with shells in hand, with the possibility of dropping one increasing as well. If I fumble a shell while loading from the bottom then it naturally wants to fall back into my palm. It seems more natural to reload from the bottom because that is the shortest path between the magazine and wherever my shells are, unless I am literally shooting from the hip of course.

Originally as you mentioned with rifles, the idea was to keep the sights close to the bore axis for more accurate point of aim at any distance. Shotguns it isn't as important, but for those of us that hunt in any and all weather, I see this as a funnel giving rain and dirt a nice easy path into the gun. Mag fed shotguns have other minor issues loading, but as you mentioned are generally quick and even more so if they have a flared mag well. I have seen some incredibly fast reloads doing the 2/4 shell reloads as you mentioned. It takes a ton of practice but it is a work of art for those who have mastered it (I am getting better, but not there yet).

There is top-loading shotgun, it called RMB-93, it super interesting weapon with tonnes of advantages and disadvantages.

I see your point about sight picture and "pointing" a shotgun, however most O/U shooters I've shot with shoot bottom barrel first and that'd be the same offset from the barrel. I would note that most good O/U shotguns have barrels which are angled so that both barrels have a similar POI at a set distance, 25 yards I think, maybe 30.

I can only really think of gravity making debris fall into the action or rain getting inside. Since fast use became a thing we've also got speed loading tubes which might be a bit awkward coming in from the top, if i'm really stretching i could say topping off is a little more dangerous since you're probably tilting the gun upward to get the right angle, if you aren't strong enough to hold up the weight of the gun you might brace it against your thigh so if you're holding the pump you might move the action during the reload process yada yada.

With modern conflicts having new dangers of small, quick moving, airborne targets (drones with a grenade) I wonder if shotguns have a potential use there, and with that new “tactical” opportunities.

The biggest reason I can see top-loading shotguns to be an issue is debris or rain falling into it. With the only area for anything to enter and the easiest place for it to drain or be removed being the cut out for the loading lifter being on top you'll have to make an intentional effort to flip it or leave the breach open to mitigate the issue

I'd imagine a major reason originally was also the entire point of pump shotguns....the "pump" is incredibly close to the tube, so it's incredibly simple to make parts work and with very little stress. If it was made as a pump action shotgun, I'd imagine it would have to 'reach' from the bottom up to the top, and thats just awkward. If its semi-auto, then it makes more sense, but then you have potential problems of having a market to sell to, since semi-auto shotguns are generally under much more control. I'd also imagine the barrel being on the bottom means its closer to your hands, meaning there are potentials for burns.

Granny could get shells in and out of her double barrel with efficiency it is top fed. Watching someone with decades of practice with any weapon is intimidating and awe-inspiring.

I can’t think of a single time in the rainforest of southeastern Alaska that I hunted when it wasn’t raining or snowing. I can’t think of a single gun where “let’s let rain wash through this part of the action” sounds like a smart idea.

My guess is because of the traditional design of bead sights. Bead sights on a shotgun are mated to the barrel. Swapping the position increases the cost to manufacture because the sights now need to be precisely aligned with the barrel. Nowadays with adjustable sights this probably doesn’t matter so much.

My guess feeds into the “hunting doesn’t need speedy reloads” hypothesis. Where do most hunters keep extra shells? Pockets, belts, etc. They traditionally don’t place them in a higher up, chest mounted rigging solution. It’s more intuitive to take shell from point A to point B then from point A, around gun, to point B.

Historically, if you need to reload a shotgun quickly you have 2 shotguns and a loading assistant to make sure at least one is fully fed.