There might be a rogue magical creature in the form of a human that gives Harry a gun. This creature could have its own reasons, like wanting to see how Harry will react and if he can use the Muggle weapon to change the power dynamics in the magical realm.
A wizard who has dabbled in the Muggle world might give Harry a gun. This wizard could have seen the potential use of a Muggle weapon in the wizarding world's dangerous situations.
In the 'harry gets a gun fanfiction', it could be that Harry is given the gun by a mysterious figure. This figure might have an ulterior motive, like using Harry as a pawn in a bigger game. Harry then has to decide whether to trust this person and what the implications of having the gun are for his own safety and the safety of those around him.
It could be a rogue wizard who has also acquired Muggle weapons and is using them to cause chaos. This wizard might be jealous of Harry's fame and wants to use the gun to prove that he's more powerful.
It's possible that there's a hidden stash of Muggle items in Hogwarts, and Harry stumbles upon it. He discovers the gun there, realizes it could be a powerful weapon against Voldemort, and decides to use it.
In this fanfiction, Harry might have the gun as a gift from a mysterious figure. The gun could have special powers like it can only be fired by him and the bullets can penetrate any protective spell. This would lead to a whole new set of adventures as he tries to figure out the origin and purpose of this unique weapon.
He could have been influenced by the Muggle world. Having grown up with Muggles, he might have seen the power of guns and thought it could be a more straightforward solution compared to complex magic spells. Also, he might have wanted to prove that Muggle technology could be just as effective in the wizarding world's battles.
It could be a dark wizard who has found a way to nullify magic in certain areas. This antagonist forces Harry to rely on the gun as his magic is useless against him in those zones. He might be a former Death Eater who has new, more dangerous powers and a vendetta against Harry for his role in the downfall of Voldemort.
Perhaps it's a story where Harry Potter is transported to a world that combines elements of the wizarding world and a modern, gun - using society. He pulls a gun to protect his friends when they are attacked by some unknown and powerful force that magic has no effect on. This could lead to him having to learn about the new rules and ethics of using such a weapon while still relying on his magical abilities.
Some might be shocked. Hermione, for example, would probably be very concerned about the use of a Muggle weapon in the wizarding world and its implications. She might worry about how it could change the balance between the Muggle and wizarding communities.
I'm not sure exactly. You might have to read or watch the story closely to find out.
In a post - war fanfic, Harry could be living in a more integrated wizard - Muggle society. There are still remnants of dark forces, but now the wizarding world is more open to Muggle technology. Harry, being a symbol of protection, decides to carry a gun as an additional means of safeguarding the peace. He trains with Aurors and Muggles alike to master the use of the gun, and along the way, he faces challenges from traditional wizards who oppose this new direction.