Just hitting the prey item isn't enough to ensure it's dead--I use my forceps for C/D. Grab the rat by the tail, and swiftly pin the rat just behind the neck (with the forceps) and pull back and slightly up simultaneously. This is a quick and easy way to do it, and as soon as the spinal cord is severed pain isn't able to be registered by the rat. Just be sure to grab firmly at the BASE of the tail...had a tail pop off once and it is not a fun thing! It's best if you have someone who can show you because it is intimidating at first.

Then just zombie rat dance with the tongs. I only have 3 snakes, but I never have problems having them eat them, unless they're just on strike. Hope this helps!