Could You Help With A More Complete ID?

Thanks. I had seen that on Wildwinds, but rejected it because of small differences on the reverse. I'm new, so I'm still getting used to the fact that small variations will still have the same RIC #. So it's the Rome mint then?

The OP coin appears to be RIC 572, Siscia mint. Bust "K" (radiate head right) is not attested at Rome. As you can see from the RIC entries below (193 is under Rome, 572 under Siscia), many varieties may be subsumed under a single RIC number while otherwise identical coins may be attributed to different mints based solely on style, which is entirely subjective. ID'ing a coin through Wildwinds is a risky business. It is far from complete and the individual entries are only as good as the ebay auctions they are lifted from.

The real answer is that different sources may group and attribute the coins differently. This particular volume of RIC was published in 1927. More recent studies include Göbl and several hoard analyses. RIC lists over 1100 #s for Gallienus, most with multiple variants. Still a lot to be learned with ancient coins and hobbyists can still make important contributions. Sometimes frustrating but much more interesting than plugging pennies into a date folder!