"three turrets" appears to be part of the attribution. Last letter in the exergue may be a "delta" mark. "It is estimated approximately that there are around 1400 different cataloged pieces (of camp gate coins), and there are at least 3-4 times more variations."
Source: http://www.campgatecoins.com/about/
Don.....
Coin 1 is certainly a CONSTANTIUS II probably Cyzicus mint Turkey as follows:
Constantius II AE3. FL IVL CONSTANTIVS NOB C, laureate bust left, draped & cuirassed / PROVIDEN-TIAE CAESS, campgate, 6 to 9 layers, two turrets, star above, SMKA [A officina letter] in ex. RIC Vol VII page 647 No 26
Coin 2 is certainly a MAXIMINUS II probably Thessalonica mint Greece as follows:
Maximinus II AE Follis. AD 312. MAXIMINVS PF AVG, laureate head right / IOVI CONSERVATORI, Jupiter standing left, holding globe & leaning on sceptre, wreath in left field, A in right field, dot SM dot TS dot in ex. RIC Vol VI page 518 No 50a
Coin 3 is unclear but appears Countermarked and may be a very worn BC Republic Denarius of some sort – difficult to research and I do not hold the books.
Coin 4 is an Antoninianus but inscriptions insufficient to ID positively outside IMP ? AVG but looks like:
CLAUDIUS II GOTHICUS circa AD 268-270 with Reverse that is really unclear except perhaps a figure standing.
1. Countermarking Roman AS coins was a practice used a lot during the Julio-Claudian period and early Vespasian. Countermarks used by Augustus and Tiberius kept very worn brass and copper coins in circulation for the troops engaged on campaigns – primarily in Germany. Claudius used them around the time of his invasion of Britain (AD 43). Nero used them to extend coinage in his early years when the Rome mint was not producing new aes. Countermarking Roman AE coinage ceased with Vespasian except in Roman Provincial (Greek Imperial) series coins where they occur quite frequently well into the 3[SUP]rd[/SUP] Century perhaps as late as AD 270-275. I have a feeling that IVOBG’s coin is a Greek Imperial Countermarked one as the lettering does not seem to fit early Roman Monogram countermarks from Augustus to Vespasian.
2. The figure on the Claudius II Gothicus coin reverse seems to have outlines which could fit the type below but it is by no means certain and is a best guess:
(SALVS AVG) Apollo standing left, holding branch and leaning on upright lyre. RIC Vol V Pt 1, no 216 Antioch mint
Here is a link for the Maximinus IIactual coin (albeit shows A rather than the Delta Officina) for IVOBG as he hasshown a coin reverse type different to our advice: