I have been told that the storage in the 50’s-70’s was over double of what is on hand today, must have been a REAL CRISIS for loaders and shooters then.
No, not at all for three reasons:
The huge military stocks and turnover policy saw vast amounts of 'surplus' military ammunition, especially 7.62mm ball dumped on the international arms market each year, much of which ended up in the civilian guntrade. Go back to the 80s, even 90s, and most range-shooters I knew owned 308 Win rifles to take advantage of the bargain 7.62 on offer. Relatively few UK shooters handloaded as a result, and only started when 'surplus' dried up (which it has entirely in Europe, can't comment on the US).
There were more factories making components 20 years ago, and
far more if you go back another decade or two. This was the remaining inherited national security infrastructure when each country needed to be at least partly self-reliant in military supplies for strategic reasons. Since then, privatisations of government arsenals, rationalization of plants by the multinational corporations who invariably ended up owning the factories, closures caused by obsolescence and/or new health & safety regulations (many historic plants had deliberately been sited close to residential areas for workforce access in the days before private transport became the norm and were now deemed to be too close to housing). All of western Europe now has only three or four powder factories for smallarms propellants, when it would have been a double figure number in the 1950s/60s for instance. This is a result too of the 'peace dividend' after the Soviet bloc disintegrated in the 1980s - we'd only ever need resources for 'police actions' and minor wars was the thinking. Finally, governments not only closed and/or sold off production capacity, but they were unwilling to fund any reserve capacity. The view was that with procurement from around much of the world, there would always be some countries / suppliers with capacity and willing to sell at short notice. Only Israel, which has faced existential threats from its neighbours over generations and fought two major and no end of minor wars in living memory, kept a defence industry geared up to a significant part of a wartime need (and even so, had to beg and borrow consumables from the US to keep its forces in ordnance during the short 'Yom Kippur' war of 1973). The UK barely managed to have enough artillery ammunition to fight the 10-week fairly small-scale Falklands War of 1982, and would have run out of naval and air ordnance if President Reagan hadn't agreed to help out.
Finally, there were far fewer recreational shooters and those that were there went through a small fraction of the ammunition and/or components that many of today's shooters need. Most formal fullbore rifle competition was geared to or influenced by service rifle shooting and in many countries, competition organisers provided military grade ammo whose use was mandatory. Even today, many mainstream UK sling shooters ('Target Rifle') don't handload. (The GB NRA contracts with private suppliers for annual 223 and 308 shipments, first from RUAG, now from GGG in Lithuania, and issues it in major matches or sells it to shooters in its NSC Bisley facilities.) A US 'black rifle' shooter will often today consume more ammunition in a few 'plinking' or semi-formal shooting outings than many bolt-action rifle users of a generation ago used in a year. Alfresco desert or whatever ranges springing up all over the place to shoot plates are a recent innovation. Finally, self-defence gun purchases have 'exploded' in the US, and the owners want factory ammunition for occasional, sometimes regular practice. Every pistol cartridge primer that goes into these cartridges is one less available to handgun handloaders, but also potentially rifle shooters too as the producers juggle production line set-ups and production run durations to meet the demand for their own factory ammo products.