The Robust-Ideal was started in 1938 as a cost cutting measure, taking the monoblock barrel construction which is a Robust feature onto an Ideal frame. I don't know when it was abandoned, likely during WWII.
The Ideal has been made with chopper lump barrels since 1907.
In 1939, the RI was made in grades 268, 274, 280, 286 and 292 with prices going from 1600FF to 3200FF, while the ideal appeared in grades 308 to 368 going from 2400 to 15,000FF!!
Best regards,
WC