I beleive you need to go by what all the top sporting clay shooters are shooting. More and more are changing to shooting tighter chokes. I regularly shoot clays with a guy who shoots Improved Modified in his Beretta auto. Even though the targets are close he still beats most of us.
A lot of English Bests were choked cylinder and full, I suppose for driven birds. I myself prefer to stick with more open chokes for target and 1 ounce #8's. When you get old you need all the advantages you can get.
What the top sporting clays shooters are shooting makes sense for sporting clays, where the top shooters do their shooting. Doesn't make sense for most upland hunting, where most shots are at skeet distances.
Re what constitutes cylinder, I think someone above spelled it out: Reach in as far as your bore and choke gauge will go. If there's no constriction from where you start to where you end, that's zero choke: cylinder. Bore could be .739, .729, .719. If that's also the measurement at the muzzle, that's cylinder. Were that not true, a cylinder bored 16, 20, or 28 would pattern differently than a cylinder bored 12. Which they don't. All should produce roughly the same pattern PERCENTAGE at 25 yards.
