As I walked down one of our tree rows, I came across three early-ripening cultivars; Faith, Gardner, and USDA 75-8-5. In cross-section, Faith and Gardner have a similar nut shape--nuts are wide and seem flattened on the suture side (photo above). In contrast, nuts of USDA 75-8-5 appear narrow when viewing the nut from the suture side but are wide in the opposite direction.
When kernels are extracted from these nuts Faith and Gardner kernels will appear much larger than the 75-8-5 kernels simply because they will be much wider. Now, look at the shell packing material that fills the space in the dorsal grooves of each kernel half. Note that the packing material forms a wide "V" shape in the Faith and Gardner nuts. In comparison, the USDA 75-8-5 nut has narrow fingers of packing material inside deep dorsal grooves. Narrow dorsal groves often trap bits of packing material in kernel halves making the shelling process more difficult. The "V" shape of the dorsal grooves inside Faith and Gardner nuts will mean that all fragments of packing material will fall free from the kernels during nut cracking.