I have a 20 gauge Encore barrel with choke tubes. I haven't checked, but I would bet that the TC tubes are the same thread and dimensions as some other brands. There is a fair amount of interchangeability amongst the different manufacturers - and the aftermarket makers sell many models. What I'm saying is not that all tubes interchange, but certain brands/styles do. I am not sure what style, thread, etc. that TC uses. Colonial arms, Hastings, Briley, are a few that make all differrent styles. You can try Cabela's, Brownells, Mid South Shooters Supply ( GBO sponsor) for aftermarket tubes. I have ordered Brileys from their website. Hope this helps...