ORIGINAL: RIStrutStopper
Draw a 10" circle around your pattern and count the hits. If you put >100 pellets in that circle in a pretty even pattern with no noticable holes, you should be good to go. That head/neck could be anywhere in that 10" circle between when you have him in your sights and when you pull the trigger. An even pattern will tell you much more than how many shots you have in the 'kill zone'.
+1
It's always a good idea to check your patterns with all your chokes.They're designed to give best results at different ranges and you need to find out what they are with the loads you'll be using.