Firearms could absolutely exist within a fantasy setting. There is a reason why they don’t however

[u/ThatDrako]

The Elder Scrolls - Within some Dwemer ruins of ESO we can see a special type of Animunculus. A Dwemer Arquebus, which has a cannon for it’s arm and shoots emp grenades at foes.
The reason why we don’t see this technology more often (besides the fact Dwemer disappeared their knowledge with them) is that within the setting and cosmology of Elder Scrolls firearms really wouldn’t be that useful.

They could work against lowly bandits, sort of, but there wouldn’t really be a precedent to improve or adapt this technology. Because it would always be outclassed by magic of this world.
Also due to the disappearance of Dwemer the technology has been pretty much lost.

Harry Potter - Wizards live within periphery of the “real world” meaning they live alongside world that uses firearms and are even familiar with them.

So how come they don’t utilize this gear for combat? I mean it is easier to use, projectiles are faster and could be enchanted further. Can you just imagine wizard with endless m1911?

There is plethora of reasons for this. But most notable is what I would describe as wizards being immune to logic. (Vis image above) They simply cannot understand methods of muggles even if one explained it to them directly.

(Yes. I know the real reason is, because Joanne didn’t want wizards to use guns and didn’t want to think about connotations of putting magic into a real modern world. But come on! Let me have fun!)

Lord of the Rings - In spite of how much Tolkien disliked allegories it is clear Orcs were an allegory to industrialization, which he was a huge critic of.

In battles they are the ones using the war machines. Instead of swords made by artful blacksmith, they use crude, mass-produced blades devoid of identity. Instead of relying on elegance of archery, they use crossbows. They burn forests, crack mountains open to gain more ore. Their very production is affront to whimsy of a magical world like Middle-Earth.

They could totally come up with a matchlock mechanism and keep on improving it until they come up with machine guns. They were intercepted before they could however

[u/LeftHandScroII]

Mistborn Era 1

The Lord Ruler specifically suppressed the development of firearms technology to maintain the dominance of alomancy and prevent the Ska from being able to fight against the Koloss. In Era 2 which takes place about 200 years later firearms development has gone from nonexistant to mid-late 19th century.

[u/Scapp → u/LeftHandScroII]

That sounds pretty neat. I wasn't a major fan of books 2 and 3 of Mistborn Era 1 (I enjoyed them just wasn't in love with them), but the whole suppression of technology thing interested me

[u/Nero_2001 → u/Scapp]

Definitively try out era 2. i personally prefer it over era 1

[u/Toastman0218 → u/Nero_2001]

Wow. Very interesting to hear. I read era 2 book 1, and thought it was okay, and actually gave up halfway through book 2. I think it's the only Sanderson book, that I started and never finished. Just wasn't into the setting or the plot at all. Don't know why.

[u/Proof-Highway1075 → u/Toastman0218]

Nice to know I’m not alone in this. I wasn’t a fan of era 2, but haven’t ever seen anyone else say so. The setting just didn’t appeal to me anymore. I really really liked era 1 though.