Ancient Roman Coin I Should Be Able To ID But Cannot.

This is a barbarous radiate from the late 3rd century. The legends are garbled and the design is a bit unprofessional as these were issued by illiterate barbarians in Gaul and Britannia. The obverse shows either Tetricus or Victorinus, usurpers who ruled over the Gallic Empire that Postumus tore away from Rome. Judging by the general letter shapes, I'd lean towards this coin being a copy of a Victorinus issue - I can make out something like VRTVINIVOMV, which could be compared against IMP TETRICVS PF AVG or IMP VICTORINVS PF AVG. If you can see it better in hand, you could probably make a better judgement.

The obverse is probably copying an obverse showing Pax, the goddess of peace, and should have read PAX AVG.

about it being based on Victorinus. (I'm reading the last two letters as an attempt at AV, personally.)

To be honest, if I remembered that Victorinus was an option, I would never have suggested Claudius in the first place.

Barbarous radiates imitating Probus are very rare. The phenomenon was largely ended on the continent by 275, following the reform of Aurelian. Some illicit minting activity, along with general lawlessness, may have continued in Britain as late as 283. Carinus took the title 'Britannicus Maximus' in 284 but the details of his campaign are lost. The portrait here with that scraggly beard has the look of Victorinus or Tetricus. Any resemblance to the name Probus in the legend is almost certainly a coincidence.