I have a old Western Auto/Revalation 16ga bolt action with a polly choke. I know alot of people use rimfire for squirells but I use this gun. Ive had several people tell me to cut that off and install screw in's. But I like the ability for the quick change of patter, just reach up and twist.
As far as still making them, Ive not seen any on NIB guns. But I have seen screw in choke tubes that is a polly choke diffrent thread fitting for diffrent guns same twisting setting as the old ones.