Maybe I'm over-simplifying things but all I'm using for turkeys is challenger 2 3/4" #4 out of a 26 inch mid 1970's full choke.
I'm shooting at 40 yards or less - except for my last jake which was an honest (stepped off) 50 yards.
Reading in another thread about 3 1/2" loads out of uber-full chokes - I'm not sure I'm seeing the benefits of that - or is this for the 50+ yard shots?