Did the guns ever have to be used (even in a bluffing manner)?

Fun fact, a significant portion of the time, having such weapons is illegal wherever they’re going, so after leaving the pirate area and arriving in port, they just… throw the weapons overboard.

This is absolutely a stupid question, but as someone who has zero knowledge about ships (especially large ones), how can they board them while sailing? Because I just can’t figure out how they can hijack them if they are moving, unless they are smaller boats where it’s physically possible to board while moving.