The female threaded post that goes in the underside dovetail, and retains the fore end. Out of stock everywhere. Available as a repro for $30 plus $10 shipping (ouch!). Been lurking on eBay for a month with none to be had. Understand why it's hard to come by (Why would anybody remove it?), but I'm building a 99 from pieces, and the barrel came bare. I would be most grateful for any offers or leads. Thanks!