PAX PVBLICA

Laureate, draped and cuirassed bust of Pupienus right, seen from three quarters back. 

Pax seated left on throne, holding branch with the right hand and a scepter with the left hand.

One coin sold the 15/09/2003 by UBS Gold & Numismatics, Auction 57, lot 433, link to the sale: https://www.acsearch.info/search.html?id=142454. 

I observe that on most of Pupienus' coins the cuirass is almost invisible and the shoulder appears smooth. Although I have listed a variant with a non-cuirassed bust for other emperors from the same period, this bust of Pupienus seems to be cuirassed. We see streaks indicating a cuirass in the lower shoulder or at least an irregular lower shoulder showing a desire to display a cuirass. Here is an example:

 On this photo the streaks are visible at the bottom of the shoulder. 

However, we cannot exclude that only draped busts exist. So far, I haven't noticed an example where the shoulder is undoubtedly smooth.