Why change it?
I think Pin Missile should have a PP buff, since all the other rapid-fire moves have like 35PP. I understand that most of them don’t have the range of Pin Missile, but Pin Missile is one of the weaker rapid-fire moves. It’s range can however be good for training Pokémon that have it (only a few).
Change into what?
Pin Missile should have at least 30PP, considering rapid-fire moves in PMU have high PP, but not range. It’s current range is (i believe) 25PP.
-Sciz