As for why he used a hand crossbow instead of silver bullets?
The reason was simple, he couldn't get his hands on them!
Such bullets, unless made by oneself, were very hard to come by, and managing to obtain a silver arrowhead from some demon hunting enthusiasts was already quite an achievement for him.
But to get silver bullets, which were technically challenging to produce, even the enthusiasts couldn't manage it.
Getting such bullets was only possible through custom orders from factories specifically making munitions, and otherwise, it was really difficult to obtain them.
And how could a factory possibly cater to his small order by crafting these bullets specifically for him?
Moreover, there was another main reason, which was that he couldn't afford the bullets.
A hand crossbow allowed the arrows to be reused, but once the silver bullets were shot, they were basically gone.
