Guns are powerful weapons and likely still the infantry weapon of choice in the foreseeable future. There are many fictional works that deals with a time period where some kind of primitive gun is available, if not outright modern technology. The Chinese usually deals with this with power inflation, like the Chinese version of Street Fighter where Ryu destroyed the universe with a Hadoken, it's probably not going to surprise anybody that guns don't work on him. Even if you don't go so far, something like the Marvel Universe where the weakest guy is someone loaded up on super drugs and generally wearing some kind of uber high tech armor would at least explain why people don't just immediately get shot and die. You can argue that in such a world people should just try to figure out how to make bigger guns instead of how to throw a shield harder but I can generally live with that. Failing that, you can also sort of just handwave and say 'no guns due to reasons', which is sort of what Harry Potter does.
But the really bad ones are the ones where you got people who look like they can remotely be considered human beings in a gunpowder world. I think there's this Japanese anime called Gate where some high fantasy world opened a portal to invade Japan and they got totally owned by police in riot gear and then the JDF invaded back and burned and pillaged the said world to the ground, and that'd be the expected outcome of such conflict. Heck, even if you're transported to say the world of Star Wars, having a gun on your side should give you pretty good odds against anyone that isn't a Jedi Master or Sith Lord. After all, Stormtroopers got defeated by Ewoks, so for all their apparent technology, armor sure isn't very good in Star Wars and a modern gun sure seems to be a lot faster than blaster bolts. About the only thing that can stop a bunch of guys with guns from the average fictional world is if that world had some certain 'requires X to hit' qualities but then that just means you need to find someone who can enchant your bullets with X. Almost invariably, such fictional worlds, if they're aware of the existence of guns, would exude some kind of hubris against the said weapons. I mean, Obi-Wan Kenobi can talk smack about blasters (which seems to be inferior to guns anyway) because he's a Jedi, and even then there are literally only a handful of individuals that can make such a statement in his universe. Most fictional worlds are nowhere near the level of power of a Jedi. Assuming there's no repercussion for wholesale destruction of fictional worlds, I'm pretty sure just rounding up a few thousand gun activists from USA on the Internet would easily thwart most fictional organization/world of gun non-believers and then some. Maybe the guys that represent some kind of primordial force of their world would survive and come back in a 100 or 1000 years, but otherwise most fictional world would be quite screwed.
The weird thing is that I'd expect Americans to scoff at the idea of random fantasy voodoo beating guns, but this doesn't seem to be the case. On the other hand, other cultures seem to give a lot of respect to guns. The New Dragon & Tiger manga in Hong Kong is a relatively low power level for guys that laugh at guns, and they only recently discovered anti-gravity and can only destroy a modern city in one hit. Even then we occasionally see the weaker guys having to dodge bullets, and that's about as low as it gets for Chinese stuff where guns aren't effective. Mind you, you'll probably never see someone pull a gun and hit Bruce Lee with it, but Bruce Lee at least has to dodge bullets too.
But the really bad ones are the ones where you got people who look like they can remotely be considered human beings in a gunpowder world. I think there's this Japanese anime called Gate where some high fantasy world opened a portal to invade Japan and they got totally owned by police in riot gear and then the JDF invaded back and burned and pillaged the said world to the ground, and that'd be the expected outcome of such conflict. Heck, even if you're transported to say the world of Star Wars, having a gun on your side should give you pretty good odds against anyone that isn't a Jedi Master or Sith Lord. After all, Stormtroopers got defeated by Ewoks, so for all their apparent technology, armor sure isn't very good in Star Wars and a modern gun sure seems to be a lot faster than blaster bolts. About the only thing that can stop a bunch of guys with guns from the average fictional world is if that world had some certain 'requires X to hit' qualities but then that just means you need to find someone who can enchant your bullets with X. Almost invariably, such fictional worlds, if they're aware of the existence of guns, would exude some kind of hubris against the said weapons. I mean, Obi-Wan Kenobi can talk smack about blasters (which seems to be inferior to guns anyway) because he's a Jedi, and even then there are literally only a handful of individuals that can make such a statement in his universe. Most fictional worlds are nowhere near the level of power of a Jedi. Assuming there's no repercussion for wholesale destruction of fictional worlds, I'm pretty sure just rounding up a few thousand gun activists from USA on the Internet would easily thwart most fictional organization/world of gun non-believers and then some. Maybe the guys that represent some kind of primordial force of their world would survive and come back in a 100 or 1000 years, but otherwise most fictional world would be quite screwed.
The weird thing is that I'd expect Americans to scoff at the idea of random fantasy voodoo beating guns, but this doesn't seem to be the case. On the other hand, other cultures seem to give a lot of respect to guns. The New Dragon & Tiger manga in Hong Kong is a relatively low power level for guys that laugh at guns, and they only recently discovered anti-gravity and can only destroy a modern city in one hit. Even then we occasionally see the weaker guys having to dodge bullets, and that's about as low as it gets for Chinese stuff where guns aren't effective. Mind you, you'll probably never see someone pull a gun and hit Bruce Lee with it, but Bruce Lee at least has to dodge bullets too.