I was thinking this for a while. When I watched John Wick back then, I really like how he has limited ammo making the scenes tense and thrilling. It was such a cool detail that I wanted to add in my stories but I feel limited when writing it and also having difficulty depicting some scenes. The type of story I wanted to write a story that is inspired by Ace Combat. But whenever I'm thinking of a scene, I feel like it's bland and not good. There's are a lot of scenarios where I want to add some action and tension, but it's hard when the aircrafts don't have the equipment or ammo to overcome it.
There are definitely audience members will poke fun at the endless ammo. However, there are still plenty of people who won't notice, and even the first group may continue.
However, you must choose which way to go. Mixing "ammo is endless and will never be a plot point" and "ammo is finite and the characters must watch their use" is jarring and makes the lack of ammo contrived.
Either one paints you into a corner. Pick one corner and stick to it, no matter how alluring the other one is, unless you decide to switch entirely.
There are two major problems with the "unlimited ammo" trope. The first is realism and the second is that it affects the stakes.
Readers know that, logically, a gun cannot have infinite ammunition, so if they notice the character has been firing a thousand bullets when they should only have fifty, there is always going to be someone who calls you out on this fact. It shatters their sense of realism and therefore breaks their immersion, and the reader's immersion is one of the most important things in any story.
If you are simply writing in a few more bullets than a single man should be able to have on him, then only the most eagle-eyed viewers will call you out. Infinite bullets, though, obviously defy all logic.
Still, it is only a problem if you are contradicting yourself. If in a previous scene, you establish that the character has only fifty bullets on his person, but he makes a thousand shots, you have broken the internal logic of the story.
Tone and genre are also important. A comedic, escapist action story with a light tone has a lower expectation of realism. You can get away with more. If you're writing a gritty thriller with a dead-serious tone, though, then audiences will expect a more grounded story.
Infinite ammo means no risk of ever running out of ammunition. This reduces the worry that the character will ever run out of bullets and misses out on an easy way to cause tension.
Limited ammo means the character has to be smart with what they do with that ammunition. When they finally run out of bullets, that's it. They're dead. The MC can't waste a single shot because they know it might be their last.
The biggest issue is when the MC has an unfair advantage over everyone else. If everyone has infinite ammo, then cool. The readers can watch an amazing gun fight without ever having to worry about people cooling down to reload their guns.
But...if the MC is the only person in the room this tool does not apply to, all they have to do is wait for the others to reload and boom, they win?
Rather than winning by their wits and intelligence, they won because they had the better gun.
Though overpowered characters are not universally bad, they do get tiresome after a point because the outcome is a forgone conclusion.
It's like putting Superman in a room of average human grunts. You already know he will win the fight without lifting a finger, so why should we care?
If you're going to give your character infinite ammo, make it clear that they have other weaknesses as well, and give them the occasional loss. Otherwise, it will feel like they're untouchable and fights will have little tension.
As a minor counterpoint the the existing answers, it is also possible for realistic ammo to ruin a scene. The audience is willing to assume that certain events that don't impact the narrative occurs offstage. As a classic example, the eating habits of the characters of Middle Earth are explained in great detail, but no one ever needs to relieve themselves afterwards. It's something that we all recognize probably need to happen, but including this aspect of realism would only detract from our engagement. The audience is often willing to believe that a new clip was loaded while we were paying attention to something more important.
My other example contains spoilers for the 1985 film Alien Outlaw. Consider yourself warned.
At the climax of the movie, the sharpshooting heroine is fighting against the last remaining alien. The director takes great pains to inform the audience that she is down to three bullets. She can't shoot at the alien, because she might miss, and she only has three bullets. She needs to move to a better vantage point, because she only has three bullets. Of course, having reached this vantage point, it would be unsatisfying for her to shoot the alien and say "I guess I have some extra ammo left over", so the first shot misses. Nothing has changed about our protagonist's situation, but the film believed that the tension has ramped up, because she now has two bullets, which is an even smaller number than three. Having discovered this tension building device, the movie immediately pulls it again with another failed shot, leaving her with one bullet. Unsurprisingly, this final bullet succeeds where the other two failed and kills the alien. If this paragraph was painful to read, I assure you that the scene was more painful to watch.
Now, I'm not saying that limited ammo can't create tension. Plenty of examples have been given about how this can work. I'm just providing a reminder that limited ammo doesn't automatically create tension. When every bullet matters, the limits are tense. When only the final bullet matters, the limits are an accounting exercise.
Most stories waive away nuances like ammo, food, toilet breaks, etc. Assuming it actually is a nuance, at least. Someone lost in a forest with an apparently endless supply of hand grenades probably needs an explanation but I don't think most readers would grasp the ammo limitations of any aircraft. You might turn off readers who are also fighter pilots but I think that's generally true of lots of things. As a software developer, I'm generally appalled at how writers portray anything dealing with software or computers but I'll put up with it if the story is good (I still like Hackers, the 1995 movie, even though its portrayal of how hacking works is goofy). Point being, I don't think it's necessary to satisfy the experts in every field, for every aspect of a story.
(Even "The Martian", celebrated for its scientific accuracy, openly admits taking artistic license with the storm that trapped Matt Damon to begin with. Mars does not have the atmospheric density to support such a storm. I certainly didn't catch it when I watched. Probably less than 1% of the population was expert enough in Mars climate to find that scene unrealistic.)
So, I generally think it's okay to ignore "nuances", like ammo, if being strict about it would ruin your idea (and most readers won't know any better anyway).
Although for non-standard equipment, it's worth noting that there are ample examples of real world pilots (and tank drivers and etc) using non-standard equipment if they can get their hands on it and think it's really the edge they need.
There are some stories you can only tell with unlimited ammunition, such as someone living in the wilderness or out in the frontier for years. Of course, unless this is some genre that tosses out the laws of physics entirely (like a farce where anything can happen if it attempts to be funny) there should be some in-universe explanation, such as bringing huge crates of it when they arrived or sporadically trading for more. “Unlimited” ammunition is of course not literal, but means the characters are able to bring a lot more than they need (But how are they able to smuggle it where they need to go, and does that leave them temporarily vulnerable?) or resupply whenever they need to (but then they depend on this, so who supplies them and could they be cut off?).
There are also stories you can only tell if they have to count their bullets. This won’t necessarily feel more realistic. Horror movies often get mocked for creating tension by making the characters get themselves into trouble only because they’re “too dumb to live.” If your readers feel that the character could have brought more firepower, and should have known they might need it, the attempt to raise the stakes might fizzle. It’s not the same kind of plot hole as having implausible amounts of supplies without explanation—the character could even think, “I wish I’d picked up a couple extra magazines when I had the chance. And a lampshade.”—but it could still fail to create drama. Trying to milk the danger of running out of bullets is only going to remind those readers that the problem only exists because the character made a mistake.
Which story do you want to tell ?
When your story is gritty, realistic and full of small challenges for the hero to overcome, when everything matters, when resources are limited and finding them is part of the journey - then you use limited ammo because that fits your story.
When your story is heroic, about large challenges and big obstacles, when the big picture matters or the inner conflict of the hero, or the relations between characters - in other words, when the small details of realism take a back seat because the story is not about them - or when resources are not an issue or a topic and nothing would be added to the story by someone running out of bullets (or being worried they could run out) - then you don't make a point of it and focus on the story you actually want to tell.
There are countless things that are ignored or passed over in stories all the time. Rarely do we see characters on a toilet unless there's a story reason for it. Eating and drinking and sometimes sleeping are often background actions or at best hinted at. Getting dressed and undressed isn't shown unless the dress choice matters or the undressing is part of a romantic encounter. Rarely do we see the hero worry about his mobile phone contract or pay for parking his car or any number of small, realistic details that - unless they contribute something to the story - are often ignored. Why would ammo be different than any of these?
The reader will create some expectation in their mind about how the story should comport with reality (usually based on genre). If those expectations are not met, the reader must reconcile and update them in their mind.
A subversion of expectation can be a good part of a story when it leads somewhere interesting that the reader can appreciate (such as a big reveal / plot twist). If the subversion doesn't lead to some legitimate development, then the reader who notices it is most likely to reconcile it as a plot error, which confuses them and/or damages their investment in the story.
Part of the thrill of realism stories is being able to use your own knowledge of the world and apply that to the story to wonder about how the conflict will be resolved. Good stories reward the reader's investment by paying of with intriguing developments that validate said wondering. By betraying the readers understanding of reality through the events in the story, you can rapidly damage their investment in this process.
Frame challenge: Limited ammunition tropes telegraph how much ammunition will be used in a story or a sequence; no more, and no less than the exact amount provided
Unlimited ammunition essentially waives away the specific details about how many bullets a person will use, and how whether they reload their weapon at specific points, but it does have one advantage that a story bringing up limited ammunition doesn't; it won't give away to a reader or viewer as to how often a gun will be used.
For example; a revolver with one bullet in it is meant to increase the tension, turning its use into a Russian Roulette aspect of whether or not the one bullet is loaded; but it's a pretty strong guess that any gun loaded with one bullet will only be shot once, at a key point in the story. It's rare for a story about a gun that is known to be loaded with one bullet to be met with "Hang on - even though I missed with that one bullet, let me reload in a few more and try again.". If it's important, the tension might be something along the lines of "This character is not going to waste this bullet on character X - there's another character Y for whom they intend to use this bullet at.".
In a similar sense, a machine gun with limited ammunition is unlikely to be used in a story where, if the number of bullets it's loaded with is important, is going to end with "Good thing we ended that climatic encounter with 29 bullets leftover."; if it does, that machine gun will likely still be used elsewhere, and it'll take 28-29 bullets to clear that encounter. More likely 29 than 28.
Which is to say, t's a trope itself to have limited ammunition; essentially an extension of Chekhov's Gun [Warning: TV Tropes link]:
"If you say in the first chapter that there is a rifle hanging on the wall, in the second or third chapter it absolutely must go off. If it's not going to be fired, it shouldn't be hanging there." — Anton Chekhov (From S. Shchukin, Memoirs. 1911.)
As a result, that level of detail can get in the way of actually telling a story where the specifications are less clear, and instead of saying "This is how many bullets will be used", writes with unlimited ammunition or bottomless magazines ask their audiences to be aware that a "bottomless magazine" will run out - if it's important for the story for them to run out of ammunition. But only where it's necessary for the story, and in their story, it's entirely possible that it will not be necessary for the story. If it's necessary for a gun to run out of ammunition at a point, it's more likely to jam or break down at that point than suddenly run out of ammunition, so as to avoid telegraphing when it'll be important for the ammunition to run out, or to hide if it'll actually do so at all.
Some of my favourite SciFi books with combat themes mixed the best of both worlds. I.e., the characters would have very advanced combat suits or space ships with all kinds of amazing armaments, some physical (bullets, rockets), some purely energetic (lasers, masers etc.). In "red-shirt" kind of fights, where the opposition was simply irrelevant, they were just quickly finished off with not a thought spared on the ammo situation and no need for weird book-keeping shenanigans.
In big "boss fights", the author had all freedom to describe awesome fireworks displays and the immense power these suits could lay down, at the beginning, and did have enough time to let the scene have meaningful ups and downs; and eventually there came a point where the available selection of weapons went down - be it through eventual ammo depletion, or damaged incurred by the enemies, and then you could easily get a situation where there was just a single rocket left which would decide the outcome of a long and protracted fight, or where the fight could actually be lost due to ammo outage anyways.
I am aware that you have the
realism tag and are not asking about SciFi, but maybe this thought helps a bit - not so much with the six shots of a revolver, but maybe you can give your protagonists some kind of arsenal to pick from, and you're not simply counting individual bullets, but the stock depletion over time.