Looking at the @dougsmit post above I believe that I have an obverse die match to his example copying the Rome mint, VIRT AVG... type. Mine copying a legionary eagle type.
I have gathered a few Severan period imitatives over the years with an attempt to focus on those copying the eastern issues where possible because that's my main focus with the official coinage, though I do get a bit distracted sometimes...... Eastern COS II and related imitations:- The first two are somewhat interesting as they are an obverse die match:- This one looks like it was was a fouree core perhaps.
The following more align with the IMP issues The first is IMP II and is very good style but not good enough. The reverse type is an exact reverse type of Pertinax and the reverse is known for a Septimius Severus from Alexandria so it isn't unreasonable to expect it on an official issue but.... no.... chalk this one up as imitative.... This on probably copies an IMP II but it could be IMP VIII This one an IMP VIII They imitated the Later Laodicea issues too
I have some from the family too..... Julia Domna - possibly silver, possibly fouree Caracalla Fourees Geta Limes/Fouree core Elagabalus Limes/Fouree core Severus Alexander Limes/Fouree core
All here is a link to a few articles regarding "limes" issued coins. Forum Ancient Coins: https://www.forumancientcoins.com/numiswiki/view.asp?key=limes denarius Lawerence University https://www2.lawrence.edu/dept/art/BUERGER/ESSAYS/PRODUCTION3.HTML. Lime coins were never minted as silver plated fourree, that is to say they were not meant to deceive people. They were typically made of zinc and not plated. They were minted as a form of currency at locations where silver and bronze were in short supply or not easily accessible. Here are a few coins from my collection: Gordian III, RIC IV, Part iii, 129 Elagabalus, RIC IV, Part ii, 55 var (rare reverse)