I too ( like Dean) found that a .555 works great for me with #9 TSS. Some found that a .562 works well for them. I like a "hot core" to my pattern so I went with the .555.
The Carlsons TSS choke I ordered for my 20 g BPS is .565 Of course, it's the backbored Invector Plus choke system. Looking forward to trying it.
For 12 g, all my guns are either Invector Plus or Ithaca Plus (Ithaca + = Invector +). I have a Browning extended extra full in my Winchester SX4 that seems to be .685. I have a Kicks Gobblin' Thunder in my A5 that is .680. I have a Briley extended in my Ithaca M37 that is .675. Using #5 lead the Ithaca patterns best. There is no detectable difference between the Winchester and A5. The Ithaca is also the only one I have that shoots exactly where I aim it. I'd like to try TSS in my Ithaca but thinkl I might need to back off to the standard full choke.
So what constructions are you using for 12 g TSS? I'm
