Look at the patterns of my Mossy Super Bantam (22" bbl.) shooting TSS.  I used two different chokes, PG .555 and .570.   I originally bought the .555 to shoot Nitro 7s.  There are a lot of high quality chokes to pick from.  If you plan on  using the Federal  load with flite control wads, a non-ported choke is recommended although I have read reports that it didn't make that much difference between ported and non-ported. YMMV.