An old brass hose nozzle emerged from my garden hydraulics toolbox when a much newer plastic nozzle failed. Unfortunately, this one leaked a bit too much to serve as a replacement, so I grabbed it in the vise while pondering how to disassemble it:
It turns out the knurled ring is threaded into the nozzle and, even at this late date, responds well to gentle persuasion with a Vise-Grip:
The washer is a lost cause, but I managed to find an O-ring that fit perfectly in the space available. Clearing some crud around the nozzle hole and buffing up the matching conical section improved its sealing ability, so I’ll call it a win.
The word ITALY stamped opposite CHAMPION suggests this thing might be as old as I am; it’s been a while since either brass or Italy was competitive in the world of cheap manufactured goods.
The Smell of Molten Projects in the Morning 
Should be reassembled with three drops of Extra Virgin Olive Oil on the threads.
Well played, sir!