The cheap Primos Tite Wad choke does excellent in most guns. Lots of guys like that choke with the Fed HW7s. I've had excellent patterns with HW7s with a nonported HS Undertaker as well in Winchoke 20ga.

For $20 each, you can't go wrong. I'd try the factory choke first, then the TW. You'll find that ammo is the most important part of the puzzle.