I would get a choke that is in the .650" , .655" , or .660" range, extended and ported. I use a .655" ported choke myself and it patterns very nicely out to 40-50yds with Federal 3" mag #6 turkey loads. You can go as low as .640" choke, but I don' t see the need to got that low. Hastings and Colonial both offer these super/ultra full turkey chokes from .640" -.675" for around the $22-$25 range.