There are some
good works on fourth century imitations, here are a few arranged chronologically:
George C.
Boon, “
Counterfeit Coins in
Roman Britain,” Coins and the Archaeologist,
London:
Seaby (1980) : 102- 188.
Pierre
Bastien, "Imitations of Late
Roman Bronze Coins, 318-363"
American Numismatic Society Museum Notes 30 (1985): 143- 175.
C. E.
King, “
Roman Copies.” Coin Finds and Coin Use in the
Roman World.
Berlin: Gebr.
Mann Verlag (1989) : 237-263.
David G. Wigg, Münzumlauf in Nordgallien um die Mitte
des 4. Jahrhunderts N. Chr.
Berlin:
Mann Verlag, 1991.
Kevin
Butcher, “The Maidenhatch Farm
Hoard of Constantinian Copies” The
Numismatic Chronicle 152 (1992): 160-174.
As far as regions, below is a map that shows were some
hoards of imitations were found. The map is from the article written by J. P.
Callu and J. P. Garnier. “Minimi constantiniens trouvés à Reims, Appendice II: Corpus
des imitations.” Numismatica e Antichità Classiche 6 (1977) : 330- 315. As stated, this map is the locations of imitations from A.D. 330- 348. The article lists the locations and
types of imitations found, and the publication information of the finds, i.e.
Numismatic Chronicle.
I also have a page on
VLPP imitations with more information, including links to other pages.
http://www.constantinethegreatcoins.com/barb2/Below is an example of a right facing imitation. There was also a right facing
Constantinopolis copy with a similar
mintmark in the Maidenhatch
hoard. This
hoard of fourth-century copies was found in 1970 at Maidenhatch Farm in
England.
Cohen also listed a right facing issue like this as number 23.
The
reverse on your example also seems to resemble the
style of a western
mint like Lyons or Trier, and was likely struck in that region.