In May 1997, the FBI officially adopted the Glock in .40 caliber for general use. Currently, FBI special agents are issued a Glock Model 22 or a Glock 23 in .40 S&W. If they fail their pistol qualification, they are issued a Glock 17 or Glock 19 in 9mm to aid in their qualification. The Glock 26 in 9mm and Glock 23 and Glock 27 models in .40 S&W are authorized as backup weapons. Special agents are also authorized to purchase and qualify with the Glock Model 21 in .45 ACP if they so choose, and members of the FBI HRT (Hostage Rescue Team) and SWAT teams are issued the Springfield Professional Model 1911A1 in .45 ACP.