I agree with ccc. Fall hunts are fun, but not as fun as a spring hunt imo. I have one friend who didn't know very much about turkey hunting and now is a turkey killing machine on public lands out west where we live. He uses an old Savage pump all camo taped up with a straight modified non choke tubed barrel and 2 3/4 " steel shot. I just shake my head, but the proof is in the pudding it's a dead Turkey at 40 yds so I know it works. I don't have any 3.5 " shotguns in fact I'm tending to use only 20 ga 3 " anymore, short little mossberg camo superlight weight youth guns with an extra full turkey choke and red dot sight. Straight win copper plated # 6's and I do pattern and sight in the shotgun on taped butcher paper, you put that red dot on their noggin @ 40 yds that old bird just flopps over and you run over and hold them down from beating themself and breaking a lot of feathers until they expire.
I would never agree a 20 ga is better than the larger ga it's not. A 12 or 10 ga is better if nothing but more shot. I just don't like carrying them if I have to run and gun, or the way 12 ga mag turkey loads kick. Another very old friend sometimes uses a side by side 10 ga, I always kid him better not kill half the flock when you drop both hammers, what a monster. I still have a few Activ 2 1/4 oz 3 " 12 ga not fun too shoot.
Maybe I'm old school, but I have the philisophy if you can't kill them with a good patterning 12 ga 2 3/4 using 5 or 6 shot they aren't going to die at a reasonable range of 40 yds or so as long as you hit them right.
You really should pattern and test loads.