9mm Largo and 9mm Browning Long are not the same. Largo is 9x23 (not to be confused with the 9x23 Winchester) where the Browning Long is nominally 9x20 so you'd have about 3mm or so of excessive headspace. The the Browning Long is also semi-rimmed so I doubt it would even chamber. Surplus Spanish 9mm Largo ammo is relatively available with some marked as non-corrosive.
On a side note my Grandfather picked up a LLAMA 9mm Largo at the end of WWII in Austria (there was a pile of pistols laying there and were told to take one if they wanted as they walked by on the way to ship back home - that "benefit" of being in a combat zone is long gone now) thinking it was a M1911, and I thing it annoyed him until the day he died. At some point probably in the 70s, he bought a box of 9mm Luger being told it was the correct ammo for it, fortunately he never fired the 9mm Luger in it (box was full) but it would chamber no problem, held in place by the extractor, and would probably have fired.