My brother has had a High Standard Shadow with an improved-modified choke that he used for years as a duck gun and for shooting geese over decoys, until steel shot became a requirement. He has never has any issues with functioning, as long as the gun starts the day clean. It you don't clean it at the end of the day, it seems like the powder fouling hardens or swells up a bit and it jams.
As long as he maintains a clean gun, it performs flawlessly. For someone shooting clays, it shoyuldn't be an issue.
Fit and finish on this example is superb, and the gun is still like new.
2&3/4" chamber.
Hope the info is useful.