It's really not hard at all to find silver with the stagbreaker. Silver only spawns high up, and only in relatively flat areas. It usually only takes a few minutes to find silver by pounding the ground. It's also more accurate than the wishbone.

The one thing you need to be aware of is that obsidian gives the same response, but you can normally tell if it's coming from the obsidian by watching where the text appears. If it's close to the obsidian, than that's likely the cause. If it's close to where you hit, you probably found silver.