"Jug choke" was a widening of the bore just before the area of actual choke restriction. Belief at the time was that it promoted tighter patterns, but nowadays seldom used. Patterns are tighter now any way. About the only time I use a full choke with modern ammunition is turkey hunting, at distances where I'd honestly rather have a scoped rifle. I use a cylinder bore now for most wingshooting....There were no splits but it was bad enough that I wanted to take it out before it grew worse to be safe. Although I've never heard of jug choked. Care to dive deeper into that? Sounds interesting