Help With The Legend Of This Constatine Era

the IIII C could be the four vertical lines for A V and the C could be G, thus AVG.

That makes the most sense for a SOLI INVICTO COMITI reverse.

I've not seen anything like that for Constantine or Constantius II, we are really going to need to see a picture when your able to post one.

In the mint mark what you are taking for an A is an R. Given the reverse type as you described it, your coin is from the mint at Rome, fourth officina in the series R*X where X is the officina letter.

However, for that series there are three coins with the same reverse, but with different bust types for the obverse. Since Constantius II had not yet been born when this series was current, your obverse reading must be for CONSTANTINVS (you omitted the third "N") Your coin corresponds to one of the three RIC VII Rome #18, 19, or 20. That is the only series that matches all of the particulars you have provided (with some corrections).

Here is an ugly RIC VII Rome #19 from my collection. However, mine is officina P, not Q.



Note the appearance of the lettering of AVG as nearly IIIIC as you reported, and the appearance of the first letter of the mint mark looking like a rounded A more than an R. The F in the right field on my specimen is in poor shape, but the appearance of the R F in left and right fields is consistent with your description.