Great advice and info already given. My $.02 .... about any Full to Extra Full choke is fine for turkey hunting. I killed a ton with a Plain Jane Savage Fox "B" SBS, 30", F/F using 2 3/4" so called "high brass" #6's. That goes back a while !!!

I encourage you to be sure to pattern your shotgun-choke combination, trying as many turkey loads as necessary to find one that produces a nice round pattern with no glaring "gaps", and a density at 35 yards so that 20 +/- shot are inside a 3" or so diameter circle in the middle of the pattern. A 3" shot shell with a 1 3/4 oz - 2 oz of #4 ,#5 or #6 shot load is plenty heavy hitting enough to drop a turkey cleanly out to 40 yards or so.

Just for grins ... try Winchester's 3", X123MXCT5 turkey loads. These patterned great out of my current turkey set-up. As turkey loads go they are reasonably priced and plenty of "ummph" to head/neck shot kill a gobbler at 45-50 yards.