The Tula, ie: Russian choke for Skeet shooting had quite an enlargement, then slightconstriction but still overbore size, then another enlargement, didn't it? I probably have this all wrong.
It was to give especially even, wide patterns for skeet shooting. The Russians dominated Skeet when it first came out.
I just googled it, but they mentioned similar design as my first sentence. I would think they wanted a shorter shot string, though, not a longer one. This would counter a number of posts as to what has been stated.
I'd think in Skeet, or any fast moving target game, that the shorter the string, in effect throwing a sheet of plywood (shot) at the bird to interstect it with the entire shot cloud, would be the best plan.
I remember reading about Tula Chokes back in the late 60's or early 70's in the Gun Digest. Short shot string, I'm sure was the object or reason for it's rather wierd design. For many people nowadays, younger perhaps who didn't see the first writings, to have the design reasons backwards, would be normal. Perhaps I'm wrong - oh well.
I guess we've strayed.