Hi everyone. New member on this board. It's been very interesting reading. I'm restoring my old (1920's) double hung windows. They have metal weather stripping (not spring bronze). Its grey in color, probably zinc and seems to be in okay condition. Maybe because the windows have been painted shut for so many years. It fits into grooves in the wood rails and stiles and interlocks at the meeting rail. Would it be more energy efficient to replace with a different sort of weather strip? If so, what? Would spring bronze be better? thanks, Mike