Need help identifying possible Roman era coin

OldDogEyes

Hoping someone can help me... A good friend of mine brought a cool looking coin over tonight to show me... He says it's possibly of Roman origin... Can anyone recognize this coin from these pictures?

Thanks...

STLNATS

Hard to tell from the scans but I think I see some of the legend of Diocletian on the obverse (name starts at about 12 o'clock) which would make it a prereform antoninianus, ca 284-93. Can't quite make out the reverse inscription (maybe a variation of Victoria Augg), but the type is Jupiter handing a victory to the emperor.

Maybe someone else can provide a different/more accurate attribution 'cause I'm not certain of what I see on the scan.