RIC only lists workshops P and Q for this one. No measurements though.
Constantine I
A.D. 318- 319
CONST-ANTINVS AVG; helmeted and cuirassed bust right.
VIRTV-S AVGG; open camp gate with four turrets, no doors; varying number of stone layers. P in left field, R in right field.
In ex. RT
RIC VII Rome 184