The unresolved evidence for the N3's 18-inch gun

Was a test gun produced for the N3, and why does its proposed shell weight appear unusually light?

The evidence is contested; no settled answer is offered, and the subject requires further investigation.

The viewer asks whether an experimental gun was made for the N3 and notes that its proposed shell weight looks closer to a heavy American 16-inch projectile than to the Japanese 18.1-inch shell. The comparison is not turned into a firm claim. The evidence remains a point of contention that requires further investigation. The exchange marks where design specifications stop providing a settled answer and primary-source work must begin.