Traveling through that strong of a magnetic field, that would definitely generate eddy currents. Like dropping a magnet down a brass plate causes it to move very slowly because the magnetic field moving induces current in the plate and the current creates a counter magnetic field. My instinct is that it would just slow it down, But that MRI is spinning magnets. Maybe it just slows down a little and is it noticeable, maybe it spins it while it's slowing it down and amplifies the minute drop due to gravity. Too bad MythBusters are gone. There's not many people out there funded well enough to test shooting bullets through an MRI machine.