Is cylinder bore the logical answer? What would happen to the gun with any degree of choke ---
A rise in pressure? A dangerous problem?
Thanks, lee

I think it would depend a lot on the type of slug. I would start with it at cylinder and test for accuracy, then try the next notch down and see what works best. The choke at cylinder may actually be larger than bore diameter, just have to play with it and see what works best.
C.G.B.

The poly chokes I owned had slug setting on them.

Just checked the one and only Poly I have and it has a slug setting just ahead of IC. Start there and work up.
C.G.B.