The weight is a little low as these usually fall between 3.5- 4.5g; but that is not a problem. You often find underweight and overweight coins. These coins were struck at X amount per Roman pound and though the weights are remarkably consistent it is not unusual to find coins outside the range. Al pezzo is fixing individual coins; but these Roman coins were struck al marco meaning the individual coin weight is less important than getting the proper amount of coins per pound. For every underweight coin, an overweight coin (or several a little heavier) would have been struck from that specific pound.
