[lugerholsterrepair]

Neil..The common cleaning rod material used during this period was a hemp like stuff..the name of which escapes me this morning. Like if you were to unravel a hemp rope. This was twisted around the threaded end of the rod and stuffed into the barrel. Got good scrubbing action I would guess.
I can't really say about the groove in the shaft..maybe like a blood groove in a bayonet? Let's the oil flow or?
You will see this hemp stuff from time to time in German cleaning kits. I have seen it on occasion twisted around a cleaning rod shaft and stuffed into an Artillery holster sleeve.
As you can see I don't know all that much about it either..maybe Gerben knows more?