Is JSP ammo better for defense than JHP?  It looks like it should be.  No, it appears that it is not.  While JSP rounds expand or deform in some mediums like ductseal or clay, when fired into animals I've seen shot with them, it appears that they act just like ball. Apparently, most handgun velocities in the 800 to 1200 ft/sec range just are not enough to cause reliable deformation of jacketed soft points.  I've not seen a human that has been hit with such ammunition that I can recall.  The folks who study terminal ballistics and "stopping power" seem to pretty well agree that the JSP ammo does NOT expand reliably in tissue.  Oddly enough, there are some soft points in rifle cartridges that seem to expand better than the hollow point designs, but such does not appear to be the case in most handgun cartridges.