 The MP 40 was often called the " Schmeisser " by the Allies , after the weapon designer Hugo Schmeisser . Schmeisser had designed the MP 18 , which was the first mass @-@ produced submachine gun in the world , and carried some resemblance to the MP 40 . He did not , however , have anything to do with the design or development of the MP 40 , although he held a patent on the magazine . 
