Suggestions on invector/winchoke

[TheSportsman]

Hey guys-
Need some guidance-
I recently cut my Benelli m2 20ga down to 21" and had it rethreaded to invector/winchoke.
Zero experience with winchoke.
Shooting 1 5/8oz 9s.
I picked up a .570 sumtoy yesterday. Was thinking of trying a Trulock .575 or .585
Any advice? The sumtoy may do everything I want. Really don't wanna go tighter than .570

[SumToy]

The thread on a choke has nothing to do with how they perform.   Only thing is some threads are thicker then others.
570 is good all around choke.   

[Ranman]

I've shot .565 to .582 in 20 gage, .570-.575 seems to be a sweet spot , for me... I bet Sumtoy in .570 will be stellar. Keep us posted.