By the end of World War II, Ideal tools were owned by the Lyman Gunsight Corp.  The company recognized that changes had to be made to the tool to make it more saleable.

Lyman decided to combine their two most popular tools (#3 & #10) into one.  The mechanism was redesigned and simplified, resulting in one tool that would reload all calibres.  Gone were the days of separate tools for each calibre.  Instead, separate dies for each calibre were created and sold.  The result was the Lyman 310.

Here is a 310 tool in .41 Long Colt.