Nice find!
9mm Browning Long is a totally obsolete caliber, and finding a pistol in that caliber is not easy. As far as I know, it was only used in FN 1903 and the Swedish M/07 (which are basically the same gun).
You can actually find Swedish surplus right now, seems like somebody brought in a large shipment a few years ago and you can still find it for reasonable money:
https://www.libertytreecollectors.co...&idcategory=12 . I lucked out and found an M/07 in original caliber, so I bought 10 boxes of 1941 production from Samco (before they went bankrupt and closed the doors
) to go with it. Haven't test fired yet, but the ammo is sure cheap enough to shoot.