The right grain bullet and all you have is jello from both lungs.That deer isn't going no where.First buck I tookIhad the scope on 9 power and he was 25yrds away if that behind me.All I seen is hair and squeezed off.I just caught the lower neck useing a 30-30.He was down.The blood poured out of him so fast he was dry before he hit the ground.I have seen one shot whith an arrow before in the neck.It never died.A friend of mine shot one with an arrow stuckin it's neck before.It depends on the angle and if I got time to let it move around a bit for a better shot, Or if I have to take a neck shot if it's comming straight on to me or partly sticking out from behind a tree and spotted me.