Not a lot to go on. Do you want to go all out old timey and use a flintlock? Will caplock be ok? Are you looking for more modern in-line (hope not)? How much you willing to spend on a smoothbore? For turkeys you will want 20 gauge or larger. If the barrel isn't choked you'll want a nice long barrel (my fowler has 46" barrel), and you will probably want to keep shots within 30 yards (if you can dial in a good pattern with it). Lots to consider.
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