Most small arms development is seen as being forward thinking, with new designs leaving the older ones in the dust. But for some, the complete opposite is the case (such as the FNC and SCAR). In this example modern day riot police in Switzerland are using chopped K31 straight pull rifles converted to fire tear gas grenades or rubber bullets against uncooperative protesters. The designation is Trnengas Werfer 73 (Tear Gas Thrower), or TW-73 for short among the police that utilize it. It is also designated as the Mehrzweckwerfer (General Purpose Thrower) MZW 73/91.
Due to the designation in 1973 from the name, it appears that the modification was introduced on the tail end of the K31s service in Switzerland, and stocks of the variant were simply kept over and used to supply the police forces, with which they are extensively used today. This appears to be a case of “If it ain’t broken, don’t fix/replace it”. Due to the seemingly built up chamber, the use of blank rounds, and few occurrences of actual operational use per year, I would assume these launchers don’t get pushed to their maximum operational capacity. That being said, they should be usable for many years to come.
Below are some videos of Swiss police in action with the TW-73. The riot police look well versed and trained in the system, firing coordinated volley’s and loading each other’s launchers. You can also see the vast amounts of rubber bullets on the street.