-sro-
Are you asking what factory load to use for turkeys, or do you want a re-loading recipe?
If you'd asked for a standard trap or skeet 12-ga load, you'd be getting several recommended loads of 1 or 1-1/8-oz of # 7-1/2, 8, 8-1/2 or 9 lead shot. With turkeys it's a little different. First, are you required to go with non-toxics or lead? My friend, olddrum1, assumes you're going to be re-loading with non-toxic. He referred you to Hodgdon's site because they are in the forefront having expended considerable effort in developing new reloading data for non toxics.
Typical factory turkey loads employ 1-1/2 oz of shot at just over 1300 fps shot in #4, 5, and 6s with the option of plated shot. This is premium ammo and expect to pay extra. These are not officially magnums, but these heavy loads are pushing the limits of the 2-3/4" 12-ga, and they'll get your attention when you light one off.
Local laws and the shooting environment should be your guide to selecting the appropriate load. If you anticipate close-in shots, go with the #6s to maximize your pellet count. For longer shots, brush bucking or unusually large birds go with the #4s with more energy per pellet. If unsure, go with the #4s until you can verify that 5s or 6s are appropriate.
