Increasing reload speed of ranged item

At some point, I tried putting it on negative cooldown (ex. -20 ticks). I don't remember if it worked though.

Don´t know if you still need an answer, but i am going to comment anyway. When creating a ranged item, you also have the option of "can use ranged item". You need a return value for this. Either "true" or "false". I would suggest creating an NBT tag for the player called "reloadTime" or whatever you want and decrease it every tick, if it´s above 0, using the global trigger "on player tick update". In the "can use ranged item" procedure you check, if the counter is <= 0, increase the timer again and return true. I hope this is, what you ment