Hello, PO must have had a great need for this tool!! Even made a hanging hook for it. Odd width, too, 7/16" . Regards, Lou

Looks like someone fashioned that from an old socket chisel, must have had a lot of tacks to pull. Maybe a carpet installer for removing old carpet staples.

Looks like it.  Is the socket filled with lead or a wood plug?

Hello, Northwoods. The plug is wood. I am going to leave it as is for now, it will go into the tack puller drawer!! Regards, Lou

That may have been made by an upholsterer for pulling out old tacks  when reupholstering old furniture?  most tack pullers are too big to get into tight spaces.

Hello, oldgoaly. I think Dan was ahead of you on that one!!!