Rossmaker - go to S & S Firearms at the following link
http://www.ssfirearms.com/Download their catalog - has lots of period fittings, etc. - scroll down to page 132 - what you arre looking for is shown on that page - item 77 (brass) and item 78 (pewter - Confederate) - they come complete with the burrs - the catalog that I have downloaded on my computer shows them at $1.50 each. What you are looking for is the "acorn" - unlike the Sam Browne which is round.
You also might try looking on the homepage for the NSSA (North South Skirmish Association) - there will be a number of Civil War Sutlers as well as leather goods folks - some of them may carry them as well. The last that I bought was from S & S but if I remember correctly (it's been a whle) I also found a leather goods supplier (Civil War) that would sell me some - they were the same price at that time as S & S so I just ordered mine from them. Good luck with your project!
For others who might be doing "period" leather work - i.e. Civil War, etc. - check S & S out - they have an interesting catalog and are good folks to deal with - they have a number of fittings for Cavalry leathergoods, etc.