RE: How many pellets in the head/neck area
I got bored a feww weeks ago and decided to pattern my 870 3" gun. I've been using a Super Full Turkey choke with Win Supreme 6's for years without failure.
On this testing day I bought a box of the Fed Flightwads in 6's. I used the Win Supreme 6's as well. I also tried a regular full choke.
The best I got was 16 pellets in the head and vertabrate. I didn't count ones that didn't hit these areas. The winning combo was the Flight wad with the regular full choke. I tested everything at 35 yards. The second best was with what I've been using for years. Super Full choke with the Win Supreme 6's. It scored 12 pellets. The longest bird I've ever attempted was 47 paces. It tumbled over and flopped dead pretty quickly. Had I known it was that far I would have probably waited him in closer.
To get 20+ seems like the next level to me. I would try to get that if my system ever failed me.