I would never throw steel at turkeys. For waterfowl it is a common understanding that to retain the downrange energy of lead, you must go up 2 shot sizes in steel. However for waterfowl you are taking body shots. Turkeys, your target is head and neck. Much smaller target and requires dense patterns of shot to ensure good hits on the smaller target. But increasing shot size in steel only ensures less pellets in the shell and thinner patterns. 180 degrees out of phase for what turkey loads are trying to achieve.
Most turkey hunters either use heavy payloads of lead or a heavier than lead alloy in small shot high pellet count size.
