What kind of action is it to sheathe reload 0 ammunition?

Reload 0 means drawing and firing/throwing can be done in the same action. What happens if you have a piece of ammunition in your hand and you don’t want to attack with it or drop it? Example of how this could happen are Shuriken with the Returning rune, or Arrow Snatching, if the DM allowed you to keep the arrow instead of throwing it back. Would storing the ammunition require a normal interact action, or does its zero reload reduce that to a free action?