Two pictures extracted from my book (page 54). They describe the different cleaning rod configuration. The first model has both the bottom and the handle ring made in tinplate to prevent damage to the bore while cleaning. In the last production the tinplate was eliminated. There is also an intermediate model where only the bottom was manufactured using the tinplate.
Ciao
http://boards.rennlist.com/lfupload/Cleaningrod.jpg
http://boards.rennlist.com/lfupload/Cleaningrod1.jpg