The American-made Ingram MAC-10/11 machine pistol was used, albeit rather limitedly, by the SAS during the 70s and 80s. The MAC-10/11 is a compact weapon that fires (sprays describes it better) 9mm rounds at a high rate (1600 rpm).
The Regiment trialed the gun for the anti-terrorist team but found it to be too inaccurate. Indeed, it soon became known as ‘the phone booth gun’ as it was said that unless you were standing next to your target in a phone booth you couldn’t hit it! When fitted with a suppressor the MAC-10/11 becomes easier to control although it doubles the length of the weapon.
Whilst the HK MP5 was preferred for most situations, the MAC 10/11 was still carried in certain covert scenarios such as in Northern Ireland when the ‘spray and pray’ characteristics of the MAC10/11 might come in handy e.g. breaking contact from an ambush.