[kanister]

After the war the guns for the Italian Air Force that were recovered from various souces;

were all verified and reworked and the mark UA47 (not JA47) means that this gun was reworked on 1947.(J is only a U broken die)
Another common mark was F.A.G. 47 or 48 or ... for the guns for the Army.

 

[kanister]

The Government needed money it would make sense to refurbish and sell left over guns.

Some years ago, two or three, the Italian Air Force sold a bacht of about 28000 Beretta '34 and many were marked UA47.
Every gun was preserved in crates: from the refurbishing on 1947.

But not every gun with the UA47 came from this sale: many were sold also many years ago.

 

[kanister]

I wonder how may F block AF M1934 Berettas they made

Till today nobody has dug the Beretta's archives so this information is not known: we can only say that the AF put in order a number of Mod. '34 at the end of the 1942 and these were delivered between the 1942 and 1943.
Beretta produced about 60.000 units on 1942 and 40.000 on 1943, all in F block.

 

[kanister]

You must consider that the letter J did not belong to Italian alphabet and was introduced only after the war: so if you insist to think that it was a J instead of a U you confirm that the 47 is the year 1947. you contradict yourself.