my first turkey i ever had a shot at was with my then new pardner 10ga, it was choked XXfull and patterned well with 2oz of 4's from a winchester western. the shot was broadside from about 40yrds, perfect picture in my mind. only i hadn't realized that the bead on the gun was too tall. i shot low on the bird with a body shot, the bird rolled, thinking it was dead, i was in the process of reloading, getting up to step on him and getting out of the honeysuckle i was sitting in at the same time. he then started running, and then flew off. lost bird.
the next year, same gun, only 2oz 6's winchester western. i killed an 18lbs jake broadside at 60yrds, DRT. the 6's penetrated to his neck bones and broke them. this time i aimed a little higher and got a solid head, neck shot.
i haven't lost a bird since. i've seen my uncles and cousins make similar mistakes at even closer ranges too. last year i watched my cousin roll a tom at about 10 yrds, later we discovered a hole in his pattern just big enough for a head and neck.
on field dressing birds that i have taken with head/neck shots, i've noticed that 6's and 4's do penetrate the wings and chest feathers, but that's about it, they usually are about 1/2" or so in the breast meat, and i've yet to see any penetration holes in the breast plate leading to vital organs.
just examples of my experiences, feel free to chew them at will. :wink: