Constans Fel Temp Phoenix

I wonder if anyone could make out the mint of this Fel Temp? The first letter could be Gamma (and then SIS?)or might be P, in which case 

could it be Plg or Ist officia Lugdunum? Thanks in advance.

 Could it be a P then ARL letters - 

N#128312 

where P is the mint master in 

Arelatum / Constantina, modern-day Arles, France 

https://en.numista.com/catalogue/mint.php?id=47 

 Then again if it is that P with SIS then one example is 

N#449543 

but most of those are with a radiate phoenix, which yours may not be. 

I think you are right, Zak, - and that explains the stroke after the P which had me worried. Thanks a lot.