JB, I use very tightly choked vintage doubles on decoyed ducks with bismuth. I have used a Super Fox, an Ithaca Super Ten and an L C Smith 3E recently, all with .043+ choke constrictions. Some shots are close, some are mid-range, some are longish. I've not seen the need to open the pattern any. Dead is dead. People talk about "destroying meat" with super tight chokes but, IMO, that is overstated. I've never had a duck mangled, from using super tight chokes, to the point it wasn't highly edible.
If you're having a problem hitting them with those tight chokes, well that's a different and understandable issue. Never been a problem for me. I've gone 6 for 6 with my Super Fox over decoys, and on two of those 6 it was a true double .......... two mallards with one shot. (I had to shoot another one of the 6 twice, so it was 6 for 6)
BTW, hand loaded spreader loads and factory spreaders, in smaller shot sizes, have typically enlarged my patterns by one or two choke designations .... M to IC, IC to Sk, F to M, etc.
