I'd leave it alone. Good caliber and easy to load. Your dies will work fine, and may already have an S-bore expander ball. Just measure it.

"B. Blindee", with apologies to PHC, isn't a barrelmaker's name, or anyone else's. The proof marks are Belgian, which means they're printed in French. Belgian rifles are proved for either lead or jacketed bullets and will be marked " B. Plomb" or "B. Blindee". B. Plombe is Balle Plombe, or "lead bullet". B. Blindee is Balle Blindee, or armored or plated bullet which, on this side of the pond, means "jacketed bullet".