The Quick and the Dead

Install the Sandevistan cyberware for its ability to slow time, and kill people whilst its active. As with some other achievements, this can take some time to get through during normal play - so keep it equipped for a while as you play naturally and try to take every opportunity you can to activate it and pop off a few enemies. Once you've reached 50 and popped it you can then swap out the cyberware for something else.