Thank you! Are you sure? It looked the most fake to me as it has a very even rim and consistent thickness.
That coin appears pitted, probably was harshly cleaned to remove encrustations that caused the pitting. Not sure why a forger would go to the trouble to copy a provincial bronze in most cases.
Numbers 1 and 4 differ from the other two that their flat surfaces are not flat at all and details are completely lacking. The Mammaea and the Philip are pretty common. The philip with its even thickness and rough surface is symptomatic for many of the issues there. Frans
Of all Roman coins, provincials are known for being the most regular in terms of diameter and thickness. For some reason, especially for larger coins, provincial flans were prepared very carefully. This coin is 100% genuine, but it could look fake due to the perfectly round flan and smooth edges.
From where I sit: #1 and #4 look suspicious. #2 looks OK. #3, I dunno, but as far as I know (which isn't saying much), it looks OK.
#1 General rule of thumb: ALL three-sisters sestertii are fake unless you buy them from a reputable auction house and they have a pedigree longer than that of a Kentucky Derby winner. #2 I presume it's a sestertius. Looks genuine to me and there's no good reason to fake such a common and low-priced coin. Here's the example in my own numophylacium. 3. Probably genuine. You'd be surprised at how carefully certain provincial mints prepared their flans. 4. Don't know enough about Flavians to say.