On both sides of the road which the retreating army had to traverse the Spaniards had placed in ambush a large force of arquebusiers. It was a weapon which Bayard held in detestation; for while skill and courage were required to wield a spear or sword, any skulking wretch could pull a trigger from behind a stone. From one of these hated weapons he received his death. As he was retreating slowly with his face toward the foe, a stone from a cross-arquebus struck him on the side. (source)Pierre Terrail mentioned in the passage above habitually ordered enemy gunners captured in battle mutilated. Even such extreme measures didn't keep him from falling to a stone from a bullet-throwing crossbow. His opponent's use of stone instead of lead made no difference to the outcome.
Gun controllers really don't credit their compatriots with much imagination or skills if they think that a 21st century person cannot make at least a 20th century level design.
Poles under German occupation were able to copy British STEN submachine guns. Would gun control advocates suggest implementing a heavier level of repression and surveillance than practiced by the Nazis to stop people from doing that today?
Looking further at the STEN, we find that the magazine and the rifled barrel are the hardest parts to make well. The magazine can be made of metal or plastic or even hardwood. The rifled barrel may be made at home, as done by many people today. But let's assume that even the basic machine tools are unavailable.
A thick enough pipe can contain sufficient pressure to be used as a barrel. Steel liners wrapped in plastic or aluminum or wood have been used to reduce weight or to make up for lack of availability of adequate pipes. Rifled barrel isn't necessary for spin stabilization, as the use of short rifled choke tubes on smoothbore shotguns. Rifling isn't necessary for stabilization in general, given the availability of plastics or wood for sabots to convey arrow-type projectiles through smooth barrels. The side effect of such an expedient is much increased penetration of things like body armor or car bodies.
But let's assume no fancy projectiles. Assume nothing but two pipes, some sheet metal (steel, aluminum, brass would all would do fine) or plastic, three springs (one each for trigger/sear return, magazine and bolt) and...that's it. A fourth spring for an extractor is optional for blowback firearms, especially if the ejection port is on the bottom. Look at this STEN-like design and envision it without the barrel jacket, with buttplate integral to lengthened receiver (which would also reduce the cyclic rate) and a smooth, unrifled pipe for a barrel. The chamber can be reinforced with a larger pipe segment to help contain the pressures. Use any shotgun ammunition, slug or shot. Sights are optional: just a front post or bead would do, or a laser pointer taped to the barrel.
The end product would fire automatically but slowly enough to make single shots possible. With loose clearances, it would leak some gas but away from the operator and generally be effective to 15-20m with shot and perhaps 50m with slugs. Would it be a viable defensive weapon? Hardly. It would be bulky, heavy and a little slow to handle. Would it make a good offensive weapon to take down state enforcement personnel...could be, but military and paramilitary troops are generally armored and at least somewhat trained, so going after a soldier or a policeman for his weapon would be a perilous undertaking. Not that the risk ever stopped Filipino guerrillas from fighting either Spaniards, Americans or Japanese troops with even lesser weapons, but they had to take heavy casualties in such fighting. When successful, they gained access to better weapons from the enemy casualties.
So for what purpose would such a weapon be ideal? Would taking out a politician supporting gun control come to mind? After all, not many politicians or heads of regulatory agencies rate effective bodyguards, nor do they wear military-grade armor with helmets most of the time. While remote controlled mines are the favored tool in the rest of the world, improvised small arms are another tool that would be available to the resisters.
Can guns be banned so effectively that they cannot be re-created by motivated people? Yes. It would require destroying all industrial capacity, exterminating anyone with knowledge of weapons or related industries (such as engine making, as firearms are merely heat engines with bullets instead of pistons) and continuing to kill off all new inventors. Such a path isn't very practical and I hope that anyone in favor of enforcing gun control legislation thinks long and hard about it even being desirable.
Some fans of gun control say they aren't against guns, only against those people -- variously defined -- having guns. That is also a pipe dream for reasons that I will address in another post. For now, meditate on the impossibility of putting the genie back in the bottle and on the risks already incurred by so carelessly informing the well-armed freedom genie of your desire. In other words, step away from the gun control platform and keep your tentacles where we can see them!