A Question for Mike Perryman

[Coniglius]

So if it was a rare gun then there should only be one or two of them in FoF and all the rest should be as in AaD. Instead IIRC every piece is 5-5 in FoF and that is what was asked why did the global rating change?

I only see 3x such counters in FoF. The problem with the gun was that it was not universally distributed in time for the battle. Very few actually made it into French OOB's.
The 47mm SA mle 1937 was designed by the French firm Atelier de Puteaux hence the 'APX' designation. It fired an Armor Piercing Capped Ballistic Cap (APCBC) round. Originally this was just an APC round (Armor-Piercing Capped) which was not terribly accurate, and did not penetrate as well (there's your 3-5 rating).
The addition of the Ballistic Cap (APCBC) increased accuracy, and minimized the loss of in flight velocity, thereby increasing its penetration likelihood (5-5 rating); much to the chagrin of German tanks who actually met them.

I imagine the colonial troops would have the older ammunition while the metropolitan troops would have had better access to the improved rounds.

More common was the 47mm mle 31 which was designed for the Belgians. These saw widespread service against the Germans in 1940. It fired a standard APC round, although a bit heavier than normal, which allowed it to penetrate even a PZ-IV. Hundreds of these found their way to Hungary after the Belgian collapse.