Investment Cast Forged Muscleback Cavity Back Quick Comparison Investment Cast A "positive" or master model of the clubhead is made, usually made of aluminum, which contains all engraved markings, scoring lines, and even the hosel hole. Wax is injected into the master, which yields a positive "wax" clubhead. The clubhead is then dipped into ceramic several times to produce the negative mold. The wax is then melted, and stainless steel poured into the ceramic mold. When the ceramic casting is removed, you have the clubhead ready to be painted. Forged Forging a club is very similar to what the village blacksmith used to do. Dies are "sunk" or cut, by milling the desired impression, and forging is accomplished with a "drop hammer". The manufacturer is then presented with a raw forging, which is a close approximation of the clubhead desired. The clubhead must then be finished by milling, grinding and drilling. Muscleback A Muscleback iron, also known as a "blade", has generally been associated as a "forged" iron. While the manufacturing process isn't really important, the design of the clubhead is. The muscleback iron distributes the weight evenly throughout the entire head, producing a small "sweet spot" in the center of the head. This is to say that a shot hit in the center of the face will produce a longer, straighter flight trajectory. Shots which aren't hit pure (off-center) will produce a shorter, unpredictable flight trajectory. Cavity Back A cavity back iron, also known as perimeter weighted, has generally been associated as an investment cast iron. Again while the manufacturing process isn't really important, the design of the clubhead is. The cavity back iron distributes the weight around the perimeter of the head, producing a large "sweet spot". This makes the off-center shots more forgiving, flying longer and straighter, than an off-center shot with a muscleback iron. Quick Comparison Investment cast Usually a Cavity back Peripheral weighting, if cavity back More forgiving, due to cavity back Stainless steel Forged Usually a Blade or Muscleback Central weighting, if a blade or muscleback Better "feel", due to muscleback design Carbon steel & chrome