Is it true that Puffed Rice and Puffed Wheat are shot from cannons?

In 1902, Dr. Alexander P. Anderson invented a process for puffing grains referred to as “shot from guns.” Recognizing the value of this innovation, Quaker entered into an agreement with Dr. Anderson to continue his experiments at Quaker’s plant in Chicago. In 1904, Puffed Wheat and Puffed Rice were introduced to the public at the World’s Fair in St. Louis, and in 1909, Quaker Puffed Rice and Quaker Puffed Wheat were the newest cereal products.