Thanks for the info.

I measured the nominal bore diameter of a couple of 42's, Winchester and Browning. The Winnies were underbored at .407 and the Browning was truest at .411. Would bore difference affect constriction, i.e. less constriction necessary to achieve desired choke when the barrel is underbored??

I'm not looking to extend the effective range of this gun, I'm just looking for the optimum chokes for Skeet(basically)
but don't want a DT Double to have the same choke in both barrels.

How about .011/.007, LMod/SkeetII ??