The Astra modelo 400 was a Spanish service pistol produced by weapons manufacturer Astra-Unceta y Cia SA. as a replacement for the Campo-Giro 1913/1916, which had also been chambered in 9mm Largo. It was the standard issue sidearm in the Spanish Army during the Spanish Civil War and also saw service in Germany during World War II.
The pistol was mass-produced and many examples still exist today. The Spanish Navy, along with the German Luftwaffe and the Chilean Navy primarily use the smaller variant Astra 300 and the Wehrmacht later altered the Astra 400 into the Astra 600 to better handle the 9mm Luger. The 400 was considered heavy as in order to handle the power of the 9mm Largo round in a blowback action the 400 had a reinforced slide and tough spring.