Oh for goodness sake! Is this going to get into the armor plated jackalope arena now??? I'm tellin' ya, two square hits with a fmj 9mm and the little energizer kept on goin' (not too far though) until it finally expired.
Guys, I could split a gut reading this. Not too many bunches of years ago I used to hunt jacks with either a 30 Luger or a 9mm Luger. The old Lugers were accurate and 50 yd shots were pretty easy if you had a good sight picture. The trick was to see how high they would jump when they got hit and I don't recall any of them actually trying to make a get-a-way until 'la morte' set in.
You could always try a soft nosed slug for a more rapid demise.................. Mikey.