Originally Posted by
rodscot
Right, think that I understand it now. It is a peening anvil and used to spread the end of the rivet once it has been pushed thru the chain to prevent it from being damaged or falling out......... or something like this.
Yes, that's correct. I couldn't tell from the picture if that "anvil" was hollow and let you push the pin through it or was a riveting face to let you "peen" the pin in place.