Why Forged Heads Vary Batch to Batch
Manufacturers publish a target spec for every model. What actually leaves the factory is a range around that target, and the width of the range depends on things most golfers never hear about.
A production run of forged clubheads moves through the same general sequence every time: a hot billet gets struck between dies to rough shape, the head gets trimmed and milled, and then it goes through heat treatment — quench, then temper — to reach its final hardness. Every one of those steps has tolerances, and tolerances stack.
Furnace Position Matters More Than People Assume
Industrial heat-treat furnaces are not perfectly uniform inside. A head loaded near a burner or a door seal can run several degrees hotter or cooler than one loaded in the center of the rack, and that difference alone can shift final hardness by a point or more. A well-run shop rotates racks and monitors zone temperatures closely; a rushed run doesn't always get that attention, especially near the end of a long production day.
Quench Consistency Depends on the Bath, Not Just the Recipe
The quench step sets the initial hardness before tempering brings it into a usable range. A quench bath that's crept up in temperature over a long shift cools parts more slowly than a fresh one, which produces a softer initial hardness that tempering can't fully correct afterward. This is invisible from the outside — the head looks and weighs exactly the same either way.
How Much Spread Is Normal
A tightly controlled production run should hold within a point or two of HRC across a full set. We've tested sets that came in tighter than that, and we've tested sets with three or four points of spread between the longest and shortest iron — from the same manufacturer, the same model, sold at the same time. Neither result tells you anything about the manufacturer's overall quality; it tells you about that specific run.
The only way to know which situation you're actually holding is to test the heads you have, not the ones in the catalog photo. That's the entire reason the tester sits at the front of every session here, before any conversation about shafts or spec.