But to be serious (at least as seriously as you can be in "what gun for demons" thread), I suppose we would really need to know a bit more about the demons' anatomy/physiology.
Why are they as tough as they are?
* Extremely tough / armoured skin?
Yes. Many are also wearing metallic armor.
* Big, strong bones?
Their bone structure is scaled up to support a 800 pound demon, yes, they're big and strong
* Redundant internal organs? (E.g. back-up heart etc)
dissection isn't complete, but it's described as 'amazingly close to human'. Some extra organs present.
* Rapid regeneration?
This is present. Not wolverine level, but 'replace a lost limb in ~ a week'.
* No actual "realistic" anatomy? (I.e. so you basically have to shoot them to pieces rather than just hit them in the heart/CNS/etc)?
Don't have to shoot them to pieces, but they're just so big and tough that their equivalent to a adrenaline response means they can often remain active for several minutes after sustaining wounds that are ultimately fatal. They also appear immune to shock.
Also, what sort of forces do they have?
Is it just infantry, or infantry and cavalry? Or do they also have flying demons, artillery demons, tank demons, etc? (And if they have flyers, would they simply be "flying infantry" that can easily get to wherever you don't want them, or are capable of performing air-superiority or ground attack roles?)
There is infantry and calvary. The calvary are mounted on what's called 'rhinolobsters'. There are flyers as well, dubbed 'harpies'. Harpies are lighter and weaker than infantry, but able to breath fire, and are fast enough to catch apaches. Their blood, however, is poisonous even to them when they're cut.
BTW, those recommending holy water and such: They may be the demons that inspired the myths, but aren't the demons of the myths, if you know what I mean. They do break known physics in a number of ways, but they're not necessarily magical. Holy water has no effect, prayer has no effect, high velocity lead has effect, and we just found out that iron can act as a sort of poison.
Oh yeah, I remember the suggestions that we use shotguns for homeland defense - but I had a thought, aren't shotguns the #1 firearm in the USA and most of the rest of the world? Combined with that the 12 gauge is the majority of those?
Anybody have an estimate on how many 12 gauge shotguns are in the USA? Maybe we don't actually need to produce any, instead hiring a number of gunsmiths to vet(and perform minor modifications if necessary) that the gun is operational and safe for the iron sabot rounds are safe in it?
Sure, we won't have but the slightest amount of standardization, but realistically speaking, we shouldn't have to be doing any real maintenance on these guns during the initial part of the conflict.
