not much to say about these, they definitely better than the plastic ones in regards to the strength and durability, although i don't recommend firing them into thick metal or concrete, it will make them bend or the flights to break, other than that these are going to be your best bet.
I fired them at fallen apples and bits of wood from around the garden, tin cans are ok too, you might want to put something behind them though, as the bolts easily go right through apples and tin cans.