Fiber handles on a long hammer are nice ain't they .
I feel every past injury as I get older and I can guarantee you that my torn rotator cuffs are due in good part to using a steel handled sledge in my youth. Get the fiberglass handle - it's worth the few extra bucks. They didn't exist when I started mining. Take advantage of modern tools, they save wear and tear.
Even better is a
fiber handled dead blow sledge. These things are really pricey (Nupla makes killer tools) but the safety and comfort factor means you can work longer and more effectively. With interchangeable "tips" you can change your sledge face to tool steel, lead, copper or even polyurethane.
When faced with a big rock that appears solid bring the heaviest sledge you can find. With another person to watch slam that rock as hard as you can. This is not a job you can do alone. Keep hitting in a pattern around the rock. Any cracks will reveal themselves as either damp lines or dust spouts along the crack depending on your environment. Your helper needs to watch for the smallest signs. Mark your crack area with chalk as you discover it's path so you don't lose track of the location in the process.
A bucket of water sloshed over the area can help after you discover a crack to find the best areas to attack. The areas of the crack that produce the highest spurts of water when you are hitting the rock show the most likely areas to be susceptible to opening up.
Feathers wedges and shims will help you keep the rock open and spread the crack until it pops. Start small and work your way up in tool size as you open the crack. Watch out for the point when it pops because there is a huge amount of energy released.
I used to work barehanded but I've found that bloody hands from handling fresh broken rock can cause major slippage of the sledge at just the wrong time. I've also discovered the time/energy equation to hard rock work. If you are willing to take some time you can usually do the job with a lot less effort. A singlejack (3 pound sledge) and the proper feathers and wedges will take down as big a rock as a 15 pound sledge with less effort but it will take more time.
Hope that helps!
Heavy Pans