In the 2 ammo opener it's after Hot Shot and before Lead Shot, alongside Potion. So,

Hot Shot, Hypercharge, Potion
Lead Shot, Reload
Split Shot, Wildfire
Etc..

You'll clip the GCD if you potion as well, but that can't be helped, there's no other place for any of those abilities. And if you don't use potion for whatever reason (farm content, dungeons, etc), then no clipping and it's perfect.