How larger guns on Hood could reshape the Washington Treaty

What changes if HMS Hood carries 16.5-inch/50-calibre guns instead of 15-inch weapons?

They could push the treaty ceiling to 16.5 or 17 inches and complicate American procurement, while making Hood's battlecruiser characteristics more apparent.

A completed Hood carrying 16.5-inch/50-calibre guns would complicate efforts to set a 16-inch treaty limit. The Washington settlement might instead allow 16.5-inch guns, or the United States might press for a 17-inch ceiling. A mixture of existing 16-inch and new 17-inch American weapons would create additional logistical complications. Larger guns would also increase the discrepancy between Hood's armament and protection. That would make her easier to recognise as a battlecruiser, particularly when comparing the overall armour scheme rather than its greatest quoted thickness.