Hi all,
The shotgun choke system consists of a knurled ring on the end of the barrel that you can twist from open choke to extra full, it all works well and I have removed it and cleaned the threads each time I have used the gun. It is a good fit on the threads and doesn't rotate on its own.
I have mainly used the gun for bunnies but when I first had it I used it for just about all the types of shooting I did. Always did well with it but that second shot is a bit slower than my double !