Interesting they have a study saying that heart wood is just as good as sap wood but they are not wanting to buy it. Can't make that stuff up..2003 US Forest Service axe handle spec:
The handle shall be Shagbark Hickory (Carya Ovata), Shellbark Hickory (Carya Laciniosa), Mockernut Hickory (Carya Tomentosa) or Pignut Hickory (Carya Glabra) of clear all white wood (two small streaks or threadlike discolored lines extending along the grain not more than 1/3 the length of the handle are permitted) No brown heartwood is permitted. Annual growth rings per inch of radius must not exceed 17. Weight must be at least 55 pounds per cubic foot (these weights are based on a moisture content not to exceed 12%). The wood grain lines shall be parallel to the cutting edge of the axe blade. No cross grain is permitted (cross grain-deviation of the fiber from a line parallel to the axis of the handle in excess of one inch in twenty inches) The handle center line shall be parallel to the cutting edge of the axe blade. The handle dimensions shall conform in all respects to drawings MTDC-632. Each handle shall have a wedging slot cut in the head end as shown on the drawing for the insertion of the wedge. The wedge shall be made of Yellow Poplar (Liriodendron Tulpifera). The wedge shall not have a protective coating. The handle shall fit snugly into the eye of the axe head (see 3.2.4) The knob end of the handle shall be chamfered. The wood shall be sound and free from knots, crooks, bows, cracks, splits, scores, or other defects that may affect appearance or serviceability.
126.96.36.199 HANDLE FINISH
The handle, including the knob end, shall be smoothly finished and protected with at least one coat of boiled linseed oil. No wax, stain, lacquer, or varnish is permitted. The protective coating of linseed oil shall be applied evenly over the surface and shall be free from runs, drips, wet or tacky spots, or other defects. Flame hardening is not permitted.
188.8.131.52 MOISTURE CONTENT
Moisture content of the handle or the wedge shall not exceed 12% when tested as specified in 184.108.40.206
It is of course much better if the hickory is air dried, but this spec was taken out by the contracting office because no contractor would bid on the handles if they could not klin dry the sticks.