Gunwolf, with all due respect, it is a "CHARGE". The top of the R is just mis-stamped.
During that time frame "La Manufacture" was always stamping the proof load on the barrel flats. I have seen that mark many, many times.
I am sure you can find many more examples on the web.
Here is one for instance, with a very clear "charge".
Many people were reloading their shells and they wanted to make sure that no one exceeded the proof load.

The proof mark is indeed for the finished gun.
I don't see a provisional proof mark, but those are normally on the tubes.
As far as I know, while it is indeed mandatory to have a finished gun proof, it is not normally necessary to have a provisional proof, it is only optional. There is a special proof mark for that (crossed lightnings). I have had at least 2 guns with that mark and no provisional tube proof mark.
Makers buying tubes from the trade normally asked for provisional proofs, but makers like La Manu did not as they controlled the entire process and were confident it was a waste of time and money.
Of course this could have changed over the years. I don't have an exact time frame for my statement.

best regards,
Betail sauvage