I've never heard that?
I've only heard about the connection of 2400 to 22 Hornet.
http://www.lasc.us/taylorpaco22hornet.htm
History seems to suggest that 2400 powder from Hercules Powder Company came about because of the 22 Hornet... at the time the powder being used was 1201 (early boxes so marked, later boxes 1204). This powder was also being used as a handgun powder... Keith speaks of it in passing, saying only 2400 far out shines it.
A report in the 1930s RIFLEMAN states that Whelen pushed Hercules to have a new powder manufactured. And it was named 2400 because it would generate 2400 plus fps from the Hornet rifles with 45 grain bullets.