I've had very good luck with Kent Bismuth shells on roosters and squirrels. Mule Deer states that while Bismuth is a skosh lighter than lead, it's close enough to perform similarly. Finding 2.75" non-toxic shells that'd use turkeys and are safe for the gun might take some looking. That said, my pard in ID has rolled a number of toms with 2.75" #6 lead pheasant loads.
For those of you interested, a former poster UtahLefty (a veterinarian) posted often about the effect of lead on raptors. A search would turn of those posts, which I found informative.
