These custom knurled nylon insert lock nuts were manufactured using SAE J995 class 8 material with zinc clear finish.  3/8-24 internal thread was incorporated with a 45 degree chamfer and a .551-.562 across the flats hex was formed over the nylon insert.  Overall length measured at .519 +/-.03" and the knurled portion measured approximately .34" in length.  This was a tricky part to tool for and to produce - it took us two sample runs to finally get everything dialed in.