Totally Uncertain How To ID

to the community

I believe it is Constantius II.

This is my go-to reference guide for all (bronze) coins from Constantine through the fall of the West.

http://www.tesorillo.com/aes/_rev/index1i.htm

It seems daunting at first, but the coins of the late empire are simple enough to understand with time.

Your coin in particular is this type:

http://www.tesorillo.com/aes/030/030i.htm

As Echizento said, Constantius II. You can see the -TIVSAVG to the right of the bust. The lack of the PF (for Pius Felix) further narrows the possible mints to Heraclea, Antioch, or Alexandria. I think your coin has the mintmark SMALE, for Alexandria.

The coin is most probably authentic. These were made on an industrial scale; tens of thousands a day at times. Genuine pieces in this shape are worth about a dollar, so there is little reason to make counterfeits.