Here is a recent eBay win. This martial bust must reference the Civil War between Constantine and Licinius. It is not in RIC; but a few examples are known--
https://www.notinric.lechstepniewski.info/7tri-135.html Constantine I
A.D. 317
CONSTANTINVS P F AVG; laureate and cuirassed bust right; spear across right shoulder and shield on left.
SOLI INVICTO COMITI; Sol rad., raising r. hand, globe in l.; stg. l., chlamys across l. shoulder, across fields T-F.
in ex. •ATR
RIC VII Trier --