unknown WW2 piston ?

All I know is that this has made into an ashtray but was brought home from Italy at the end of the war which may suggest not allied aircraft ?

The crown is evidently convex (domed ) but unlike a Pratt & Whitney piston.

Diameter measures approx. 145 mm (merlin 135 mm)

The forge manufacturer numbers read :
BACE 64 A5P
963A 6P
There are traces of four or five inspection stamps but are barely visible…….

Can anyone of you engine buffs out there, throw any light on the subject……??