Rules:
Any Falling Horseman with
head decorated (laurel or other) is
Constantius II except for a very, very few large module (21mm+) that are
Constans.
Constans is
rare enough that it is safe to say that a coin that is not clearly
Constans is 99.99% certainly Constantius. Any small coin with decorated
head is
Constantius II.
Bare head coins are
Constantius Gallus (any size) or
Julian II (only small) but the great difference in their names makes it relatively easy to separate them with only a few letters. The exception to all this is a super
rare coin of
Magnentius but if you are lucky enough to find one of those one in a million coins (figure of speech, they are probably more
rare than that) you don't need to be reading the drivel from guys like me. If you have one, prove it to me and I'll apologize.