American-built shells for Richelieu's French guns

Were the American-built 15-inch shells for Richelieu super-heavy, and were they American shells adapted to French guns or a new production run of the French design?

The answer recalls them as heavy rather than super-heavy, subject to French breech compatibility, and describes their manufacture as an Americanized version of the French design.

The initial answer recalls Richelieu's American-built ammunition as heavy, but not super-heavy in the American sense. That classification is offered from memory. Compatibility with the French breech is given as the constraint on the projectile design. The follow-up describes the manufacturing solution as an Americanized French design, placing it between a standard American shell adapted to the gun and an unchanged copy of French ammunition.