I have a SumToy .410 choke. He threaded my barrel and installed the choke so I'm not sure on thread pattern. I've shot 8-10 rounds through it and have never hunted with it. .387" when I measure the inside diameter with a caliper. $60 shipped in US. PM if interested.
If you call him he should be able to tell you what threads or it might be on your invoice It will help you sell the choke
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Thanks