During Hero Mode, the player is given the Hero Shot. The player can upgrade it with Power Eggs to increase its rate of fire (x1.2, x1.5, x2.0). In order to get the Hero Shot Replica blueprints, the player needs to get an Inkling Squidamiibo and play its challenges. The blueprints are awarded from the fifth boss challenge.
When the player finishes the challenge and defeat DJ Octavio, the player will get the blueprints made by Ammoses Shellendorf, Sheldon's grandpappy. If the player brings the blueprints back to Ammo Knights, Sheldon will only give the player a replica of the blueprint as he cannot copy the technology inside. Even though it looks like the Hero Shot, it is only a replica and it has the same stats and weapon set as the Splattershot, and it just looks cooler.
"A sweet replica created by Sheldon from his grandfather's blueprints. It looks funky fresh, to be sure, but apparently it's just a regular Splattershot with a fancy paint job..."