I offer a vintage M400 green striated fountain pen with piston filler and a M (medium) 14K nib.  The pen has been fully serviced and has new seals so it works perfectly and writes very well with great ink flow.  This pen is from the 50s with best German workmanship! It is vintage, so nib has some bite to it that can be perceived as scratchiness...but is normal, even desirable.