I think the main reason for the switch to semi autos was they needed to be able to defend themselves better if they ever got involved in a fire fight with the bad guys.The drug trafficking changed a lot of things for law enforcement officers in the late 1980's.Those guys were sometimes heavily armed with auto weapons and the officers were really out gunned carrying a S&W revolver.

~Molɔ̀ːn Labé Skýla~
As Bob Hagel would say"You should not use a rifle that will kill an animal when everything goes right; you should use one that will do the job when everything goes wrong."Good words of wisdom...............