Carnt really work out the sizing for leggings / gaiters? can anyone help?
Also should i get wool or HBT trousers for my us Infantry impresiom?
Cheers guys
Wool always looks best - plus it is in fact cooler in warm weather, and warmer in cool weather, so a win win there.
in regards to the leggings, I am unsure. I wear the standard size 3 - which is what most people are - but there may be a calf size/size chart that someone else knows of?
Cheers for that 
Got yet another question though 
Wool shirt or hbt shirt?
the answer is the same as before, the wool shirt is generally a better bet.
HBTs were supposed to be used as work-wear, to stop what your uniform getting mucky. Famously they were worn by those Rangers on D Day, but normally they were not a 'combat' uniform. With the wool shirt and trousers, you cannot go wrong.
Many Re-enactors wear just HBTs, as they are more comfortable to stand around in. But I have found the wools give an extra layer of warmth in the cold, and breathe better if you are moving around in the heat.