The same system is available in 37 mm size for police . The 40 mm model has a rifling of 1:1.224 , is 900 mm long , and weighs 4.4 kg ( 9.5 lb ) . The same system is available in 37 mm size for law enforcement agencies The 40 mm model has a rifling of 1:1.224 , is 900 mm long , and weighs 4.4 kg ( 9.5 lb ) .