Looks like a reload, chuck em. Somebody may have used a .451 bullet?, looks like the neck is bulged. Something is not right. Lucky you spotted this. I've done something similar with 45 colt, I did not have the neck sizer set right and was splitting cases.
If it was needed to save my life I would fire it, but other wise no. Even if the split extends, the worse would be some gas coming out of the revolver. Probably would not injured the hands of the shooter, but still I would err on the side of caution not under range demands fire it.
NO! I discard every case with a visible crack. The crack is the visually observed damage. At the rim end of the crack: the brass is already weakened/thinned by the force of the crack "spread/width", it just hasn't separated yet.
There's also a major reduction in case to projectile seating friction and broken crimp tension. Without proper tension/crimp: he projectile could seat further back in the case and cause over pressure or shift forward and jam the action before it's fired.
Pull and recycle the bullet/powder. You could try a wax wad to see how the primer would launch it or just kill the primer and trash the case. I crush bad cases that I keep for brass recycling.
I discard the brass if I see a visual crack. Meaning a fraction of a millimeter. I've marked them before to see what will happen. And they split when they are fired.