>If you were close to the end of the arc you could, theoretically, catch the bullet in your hand since it’s speed is approaching zero.<
We used to have some mortarmen whom you would love to play catch with.
Since you don't seem to know the difference between a bullet and a mortar why bother. Same applies to the word theoretically, which has a meaning.
A bullet is an inert mass. Mortar rounds tend to be filled with stuff what goes boom. Not the same thing at all.
Now, if you're using mortar tubes to fire tennis balls -- something you can do with PVC pipe and hair spray as propellant if you're bored next weekend -- give me an outfielder's glove, and that could be a game. Fly balls only -- no line drives.