Depends on the spreader shell you choose, as well as the individual gun in question. Using a Polywad factory spreader load, I got very good results through the tight IC barrel (likely close to your skeet II or LM) of an Ithaca Classic Doubles 20ga. Eventually decided to have all the choke taken out of the R barrel of a Sauer 20ga. The spreader pattern through the ICD's IC choke was not quite as open as true cylinder, but pretty close. For me, because I live in grouse and woodcock country and have the opportunity to hunt them quite frequently, it just made more sense to modify a gun so I could shoot regular loads through it, saving the trouble of reloading spreaders (or the expense of buying them). Since I had that done, I've also discovered that a cylinder bore throwing 3/4 oz of 8 1/2's at skeet birds also works very well.
