I worked on my photography and got a clearer pic this morning. Circa 22 mm. (don't have a caliper) and 4.66g. I thought Caracalla at first based on the portrait but Wildwinds listings are much more similar to this, for Gallienus. It's hard to tell, but I think a radiate crown is present on this. This was one of the unattributed stocking stuffers.
Sure, it's Gallienus I have a specimen on which the legend is easier to read Obv. : IMP CΛE R ΛGLL[OVNΛHHIR], radiate draped and cuirassed bust right Rev. : ANTIO - CH OCL, eagle on vexillum inscribed XX between S R and two standards. RPC X, — (unassigned; ID 63323) The legends on this coinage are usually blundered, the celator engraved the second letter first : "AGLL(ienus)" or "OCL(onia)". That's curious.