Leg color should be according to standard, but hatcheries breed for production quality over standard. True Ameraucana would be grey or slate, sometimes willow depending upon the color. New Hampshire should be yellow.
You ordered Ameraucana, but only a couple of hatcheries actually sell true standard Ameraucana selling instead what is called an Easter Egger (sometimes erroneously Americana). The brown legs I suspicion are more willow than brown and the hallmark of the Easter Egger (a mix of Ameraucana and any other breed typically bred in hatcheries). So you would have received, most likely, 16 Easter Eggers.
The New Hampshire Reds would be technically Production Reds as the standard breed name is New Hampshire (no red). That indicates more Rhode Island Red thrown into the line, leaving standards for New Hampshire for production (egg quantity).
So it looks like you have some very nice hatchery quality Easter Eggers and Production Reds. You should get lots of brown and green eggs in about 5 to 6 months.
If the legs are a true brown, and the chick grows up with brown legs, then it is either an oddity indicating some other breed by mistake or poor standard quality as to leg color. Odd things can happen in genetics when you mix a bunch of breeds as happens in the hatchery formulas.
LofMc
Info about the New Hampshire:
http://www.motherearthnews.com/home...mpshire-heritage-poultry-zeylaf.aspx?PageId=1
Info about Easter Egger vs. Ameraucana
http://www.the-chicken-chick.com/2011/09/ameraucana-easter-egger-or-araucana.html
