if you are 6' tall or taller, a short jacket is actually very accurate and was not uncommon to have clothing too small or too large. We have to remember that alot of reproduction gear that is made to the period correct dimensions is now and would have been in the 1860s too short on a taller man but he would have carried it/worn it anyway. Its also a myth that everyone was tiny then (they were not 200 + lbs either but that is a different discussion). Yes the average man was shorter but there were still plenty of 6 feet and taller men. We spend so much money on clothing and equipment that we want it all fitting perfectly and properly tailored to our bodies, but issued gear was not that way.