Reloading (ammo) is quite cathartic to me. I don't know why, but the repetition of it and the extreme accuracy and carefulness is very relaxing to me. I don't understand why, but it is.
The results of it also is fun, getting to put a small group at distance. Very satisfying for some reason. I guess the quietness, the deliberateness, and needing to take your time to be as precise as possible.
But I warn you, it's not a cheap hobby.