Have been available legally since the late C19th (along with bolt actions). Most folk go with a double barrels (most side-by-side but some under-and-over) because they are lighter, yet you can still get that second shot off quickly (or simultaneously) if needed. Most folks (traditionally) used shotguns to hunt small game, especially birds where more than two shots without reloading was less likely and had to be weighed against the additional weight often lugged through cloying swamps and other treacherous ground. All along however some folks had a need for multiple shots or hunted larger (sometimes dangerous game) where a multi-shot shotgun firing ‘buckshot’ (.30 gauge pellets) or solids were needed.
Nothing has changed. Only the law. There has been no increase in firearms offending by law-abiding gun owners. Practically all firearms offences are perpetrated by unlicenced users with illegal firearms. A further restriction on legal firearms owners does not make the public safer. The contrary is the case. Rather than outlawing the Adler shotgun (and all other lever action shotguns – I favour a Winchester .410 lever action for Della for example), law-abiding folks ought to be allowed to carry handguns for self-protection.
Neither the law nor the police protect you. At best they make you less safe and/or mop up the pieces (and apportion blame) afterwards. A ban on lever action shotguns will also only lead to a call to outlaw lever action rifles (like the ones you see on Western movies for example). I admit I mostly use nothing but lever action rifles. It is not so much their quick second-shot capability which attracts me to them but their quick first-shot capacity from unloaded – a configuration which I always prefer over relying on ‘safety catches’ which are arguably the cause of more unintentional gun incidents than anything else!\
1887 Lever Action Shotgun ‘Terminator’.
PS: An 8 cm long metal tube approx 2 cm in diameter is what separates the two sides in the ‘Lever Action Shotgun Debate’. This is nearly of the level of nicety as the ‘Little Endians and Big Endians of Gulliver’s Travels or the two sides who tore each other to pieces centuries ago in what Gibbon described as the war of the Significant Dipthong’ when two words (now unspellable with a Qwerty keyboard) between the ‘Homoousians’ and the ‘Homoiousians’ all but destroyed Christendom. Was Jesus of the same kind or of the same substance as God? Somewhat therein as I recall swung the bitter dispute (At last settled by the Nicaean Creed you may have been taught at Sunday School). Five shot Adler lever actions (with a tubular magazine holding four shot-shells are permitted, but a very like tube holding seven shots is the scourge of the ages and a source of indescribable peril from which the public must be protected at all costs (whilst the venerable .303 Enfield which saw sterling service for us in two World Wars with its 10 shot magazine (in its heyday, and arguably still the ‘fastest bolt action rifle in the world’) is freely available…Ah, the sanity of it all!
PPS: I would have thought it less than academic how dead you would be after you had five 20mm holes blasted through you (eg with 12 gauge solids) as compared with 7-8 such holes, but i am only a layperson! The pollies clearly think it makes a big difference.