Thanks to all who replied.
My model 42 seems to be choked very tight but I have no way of measuring the choke.
But it seems strange that Researcher's modified barrel measures .009 and Replacement's full barrel is only .002 more. Silvers' full choke is about .015(assuming the bore is .410).
I wonder if Winchester changed the choke constrictions for the model 42 over it's production life.