Collisions and spirals of Loewner traces

In one aspect, a correlated set of individually numbered golf club iron heads progresses from a high numbered head to a low numbered head. Individual heads have a front striking face, a rear face, a sole, a toe, a heel and a hosel. The front striking faces of heads within the set individually have a total planar area defining a progressively decreasing loft angle in going from the high numbered head to the low numbered head. For at least two chosen pairs of heads within the set, the striking face total planar area of individual heads within each chosen pair increases in size in going from the higher numbered head to the lower numbered head in the pair. In another aspect, a correlated set of individually numbered golf club iron heads comprises at least a 3-iron head, a 4-iron head and a 5-iron head. The hosel is provided relative to the sole to provide a different and increasing lie angle in sequentially progressing from the 3-iron head to the 5-iron head. The heads within the set define a 3-iron and 4-iron pair of heads and a 4-iron and 5-iron pair of heads. The sum of the differences between the lie angles in the 3-iron/4-iron pair and between the lie angles in the 4-iron/5-iron pair are less than or equal to about 1.0 DEG .