What you are looking is part of Belgium's proof markings system. The PV stands for "Poudre Vive" (smokeless powder). The "Y" I cannot explane, as that character does not appear in any of my references on Belgium proof marks. FN did make a "Y" series of Auto 5s but none of them were supposed to have been imported into this country and that "Y" desigation should have been part of the s/n on the underside of the reciever. You should take another look at this "Y" an insure that it is indeed what is stamped there.
The markings on the receiver and barrel will tell.
You will need to supply a serial number to get the correct answer to your question.
The Stamp on the guns.
Check the receiver and barrel
Receiver
1942
Usually on the receiver.
on the bottom of the receiver
Check the receiver.
On the receiver.
On the receiver.
On the receiver.