7,5x54 MAS or 7,62x54 rimless?

I have a cartridge made by FN in 1940, or so the HS indicate ( F N 40 )
The bullet dia is 7,88 mm, the case lenght is 53,6 mm.
Bullet is a ‘normal issue’ military pointed Cu-jacket.

In my view it is the standard Belgian military rifle round, a 7.65 x 54 (or 7.65 x 53, depending on the country) Mauser, first adopted in 1889.

I had an idea that the x53 cartridge as used in South America was somewhat shorter.
Thank you