Could Ireland survive without importing anything?

The country would be a prime target for invasion and colonisation. Any country cut off completely from imports would be uniquely weak in history. If there is a Farage type government in the UK, they could see it as a chance to reunite the Kingdom.

We still imported grain then, through Irish Shipping Ltd, I imagine a quantity of that went into cattle feed as well as for bread and brewing.

We didn't starve in the war, but we were not well-nourished; there was real food insecurity — that's why we had rationing. We were exporting beef and dairy, not so much because we had surplus food as because we needed something to trade for oil, coal and other necessities that had to be imported.

Plus the population today (5.01 million) is 70% larger than it was in 1946 (2.96 million).

Shur you can't beat a good freshly picked crab apple.

We have more people true but we have much more capacity too. I know the loss of foreign sources of fertilizer etc would impact our production but alternatives could be found and even if our capacity was halved (unlikely) we still would have more than enough to feed our population.

If we couldn't import energy, society would more or less break down. How would we generate electricity? We couldn't farm on a large scale so our food production would probably be down 90%. Food would be very limited. We are only 3 meals away from people getting desperate. No tractors or other agricultural machinery. No transport. No medicine. No food processing or manufacturing. No water treatment etc.

I can fish, have guns and lots of ammo so I could hunt. I don't think I'd starve or be an easy target for someone trying to take my stuff.

As for most other people, it's hard to see how they'd survive a couple of winters.

Here on planet Earth, guns are quite often taken off those who have them. They are among the most-stolen items in the US. I would expect something similar in the Brave New World we are contemplating here. Both guns and ammunition (which, as time went on, would in increasingly short supply, since it couldn't be replaced once used) would be prime targets for theft.

US is awash with gunsso no wonder. I'd imagin ein such a scenario they would be prized and carefully hoarded?

Likewise, being able to produce bullets will soon become very important. It is something one can do at home in small quantities, with some training and specialized equipment, but all of that would become super high value as well.

Yes. Lead is still pretty commonly available. Copper is sufficient for jackets.

Black powder is doable with potassium nitrate (here, horsey horsey), charcoal and sulfur. Nitroglycerin would be much harder and dangerous to make, but hey, https://www.youtube.com/results?search_query=how+to+make+nitroglycerin

If you want to make smokeless powder, you need nitroglycerin and clay. Nitroglycerin is used mixed with clay for smokeless powder which is what is used in most bullets. Dynamite, too.

I am far from current on the techniques, having left the USA a fair few years ago, but that's the gist of it. Mucking about with this stuff is nasty business, too, lead fumes, ughh.

As for specialized equipment, if one is content to slowly produce one cartridge at a time, I don't think it's particularly hard, you basically pour gun powder into the brass and crimp a bullet onto it.

One other thing is you'd need primers, hmm, no doubt there's a youtube video for that. Likewise, you can make cartridges from used copper pipe.

Copper was used prior to brass in the old days, it doesn't work nearly as well tends to deform badly, but when it's all you have….

Hmm…youtube keeps giving: how to make home-made primers:

Not any more there aren't.

How do you make biofuels with no imported energy? Hydrothermal requires electric pumps. How do you transport peat and coal? Horse and cart is all we'll have without importing fuels.

Mining coal and harvesting peat would have to be done by hand.

Solar/wind equipment wouldn't last long without spare parts lubricants etc, 99%+ of which we would be able to make.

We'd be back in the 1700's if we couldn't import anything.

Somewhere along the line the infrastructure would break down. It could be at the electricity generation end or the supply end or at house/business end. It could be something big or even as small as a fuse or a lack of hydraulic oils/lubricants etc. and I'd guess we wouldn't have the capacity to make fuses or much else really without importing materials, machines etc.