This Thompson Center manufactured rear rib screw is also known as the ramrod retaining spring screw and is for the Hawken muzzle loading rifle. This screw is in very good condition with light slot wear. (file photo)
Note: Thompson Center Hawken muzzle loading rifles with the following serial numbers have been observed with this part:
Percussion: 73609, 111807, 141298, 275512, 368920, 437565, 443697, 457004 & 489495
Flintlock:
Kit in Percussion: K145177 & K188746
Kit in Flintlock: