The Southern SXS has a Robin Hollow 24 gauge tournament and Vintage Cup has a 24 gauge class as well. However, less than handful of people shoot 24 gauge SXS and only one or two shoot a 24 gauge hammer so your chance for a high finish are pretty good. So bring em on out the Vintage shoots!

Also the most recent Shooting Sportsman Sporting Shot has an article on 24 gauge guns on page 14: http://bluetoad.com/publication/?m=18740&l=1

"When you have to shoot, Shoot! Don't talk." - Tuco