I have found a Bowie knife that has an interesting butt cap that is no later than 1955, based on the Moore sheath. Not sure if its been discussed before or not.
It appears that the buttcap is either peened or an inverted nut. Hard to tell. Have you seen this one?
Link to it
http://svalbardrepublic.org/ebay/ran...e0512-bak1.htm
Regards, Samg