Argentino M1879 Rolling Block. Is it worth restoring?

[Claven2]

Another idea is to get some similarly sized fishing lures or other soft lead plug and a piece of steel flat bar. On a solid surface like a tile floor or a piece of sheet steel, roll the plug under the bar while putting pressure on it. Measure often - it will elongate and the diameter will shrink. When you get within 5 or 10 thou of the calliper measure groove depth, stop. You now have an appropriate slug.