Thanks for the leads!
Niklas, I had that same thought regarding going a size smaller. Seems like it would spread the top opening a bit more, yet be just as functional.
Dave,
Exactly. In addition, before I put a new one on, I bend the edges (that will be adjacent to rib) doown as much as I can, so that they lay even closer to barrels. For me one size smaller makes a big difference, in part because I shoot tight choked guns and take some care to center patterns. Mostly, I hunt ducks, geese and pheasants, all birds where there is time to make sure all is right before tripping trigger.
Niklas