Shoot all the birds you want in body with 4's and you will collect darn few of them, even birds that are at 30 yards. Some of us old farts like to call birds in closer than 40 yards and have developed the patience to pass on those so called 50 yard shots.

A pattern board and a paper target will stand still at 50 yards and a tom doesn't At 40-50 yards #4 shot from a rapidly opening pattern do carry the energy to penetrate into the body. But... that load may not have enough pellets bunched tight enough to crack his skull or break his neck this requires multiple pellet hits unless you eye ball or ear hole him. Those body hits from such a load provide a slow death for old tom.

I began my turkey hunting career long ago with a Browning Sweet Sixteen and a 1 1/8 ounce load of #6's. I now use a 3 inch load of #5 copper plated lead in the Federal Flite Control rounds. I agree with you on energy transfer but even a #5 typically won't do deadly damage on a body hit bird that flys or runs away after the shot. My favorite shot size is still the number 6 but my current turkey gun and choke of choice will pattern the 5's better than the 6's.

Killing a gobbler quickly and cleanly requires a hit in the head and neck area from a dense pattern of shot applying multiple hits to the neck bones and skull. 7.5 and 4 are at the extremes on both ends of the stick. #6's and #5's provide enough weight and density to accomplish this at any sane range.

One more thing, just because it is the last hour of the last day there is no excuse to take a marginal shot at any animal. We refer to that as sportsmanship.

A veterinarian buddy of mine x-rayed his last 7 or 8 birds and discovered there was no more than 2 pellets in the head and neck of the birds he has killed. A few only had one peice of shot.

Personally I have never shot a bird over 30 yards. It's just too much fun calling them in close.

Scratch golf similar arguments are used for heavier larger shot for duck hunting and retained killing velocity of a BB, 2, 3 vs smaller 4,5,s and that has some validity, most ducks I clean have 1-3 pellets through them, and I like them to be bigger pellets, but I went hunting with remington high speed #6's in 16 gauge and I didn't feel under powered for a gobbler within moderate range. Whatever you feel comfortable with will work, but don't blame the arrow.

To answer the question, a good load is somewhere in between. I like 3" #5, but I've been thinking about using 6. Not in need of any range extensions, so 6 will do fine.

OHH - Turkey loads are usually pretty slow. High payloads make for slower velocities. They already kick pretty bad. To get turkey loads going at good waterfowling velocities would be murderous.

"I like big ole wammy shells you know for when you want to put a big ole hole in something." lol rough quote from the dukes of hazard movie. I use 3 inch mag in my 20ga remington 870 express and have no problem putting a bird down at 30 yards. I should mention I use a modified choke otherwise the patterns all over the place at 20yrds.

When I did Hunt Turkeys with a shotgun, I used Win.
Duck&Pheasant Load 12ga/2.75",1.25oz#6..or Rem,Duplex
12ga/1.50oz#4x6, load all on full choke,Great 40yd stopper's...I never Felt the need for 3"or 3.50" chamber to kill a turkey, JMO!

Capstick put it best:

"Pattern density, NOT shot size, kills."

Bubba

Yep, Shane, I can appreciate the difference in the loads. If you're not going to have the velocity then you gotta have compensation with inertia - lead and large enough shot to take out their central nervous system. With steel for waterfowl we have to compensate with velocity and therefore sacrifice the density of the load. But we're not making head shots either. Everyone is bang on about calling and patience. Same holds true for goose hunting. The guys with the 3.5" "roman candles" trying to bring down geese floating around fifty yards up in the sky wreck it for everyone. And by everyone, I mean the geese too. Probably half a dozen crippled ones flying off for every one that drops. Any bird that actually comes in to respectable range is going to get blown to bits. It's all about showing off for these guys. And marketing for the companies that develop this stuff.