BT, My first couple of birds were taken with Duplex 4x6 shot out of my old Ihtica 2 3/4" pump gun with a full choke. The first gobbler was taken at about 25 yards and was dead before he hit the ground. The second took awhile to expire.
My new Rem 870 SPT gun with an Xtra-full rem choke likes #6's pretty well, and dropped a tom @ 35 yards last spring. I am planning on getting an aftermarket choke soon, and will hit the patterning board. I plan on using the shell (4,5,6,4x6) whichever patterns best. I will be very confident with my selection.