We do not use metric system anywhere. First of all gauge system for long firearms. Steel water pipes dimentions are in inches still, 1/2", 3/4", 1" etc. Vehicle wheels are in inches as well, 13, 14, 15, 16 etc. And I guess a lot of different stuff I can't recall right now.
Actually everybody has to use those systems he's been learned and used to use, otherwise it would be disaster wink


Geno.