Matthew, it doesn't appear that the threaded barrels are available separately. I would contact Tisas directly at Info@TisasUSA.com

Matthew, tisas does make a 5.1 inch threaded barrel version but I can't find a replacement barrel anywhere for sale. So I'd recommend contacting the manufacturer, I'm sure they'd be willing to sell you the threaded barrel. You can email them at " info@tisasusa.com " or here's a link you can use to contact them. Sorry but hope this helps, link here................ tisasusa.com/article-a/261.htm

Matthew, I would contact SDS Imports (Importer or TISAS Handguns) and see if they can acquire or direct you to a replacement threaded barrel at info@tisasusa.com ------------------ tisasusa.com/product-p/px9tnsf.htm ----------- Cheers and stay safe!