One of the most identifiable gadgets of Batman is the grappling gun ("Bat-Rope"): a launcher that shoots a grappling hook and enables Batman to pull himself up to the rooftops.
However, in almost all adaptations it seems that Batman has an unlimited supply of ropes. Moreover, in most adaptations, he even does not need to reload, and whenever he draws his grappling gun, it is loaded with a rope and ready for action. It is possible that he reuses most of his ropes when he pulls himself to the hook, but still - it doesn't explain how his grappling gun is always loaded and never runs out of ropes.
How is Batman's grappling gun always loaded and ready to use, and never runs out of ropes?
Batman vs. Superman("The Flash", 1:26 to 2:32 )