I have personally participated in two attempts to fire federal civil service employees, and observed a couple other attempts up close. None were successful in terminating the employee for cause, altho in the two cases I participated, ultimately the employees left civil service.
It is difficult. See "Merit Systems Protection Board." Better yet, The Donald and Congress should take a look at it.
only the actual examiners are government employees, those whom have their signatures on the forms. Almost everybody else involved in the NFA process is either a contractor or a temp.
When your FFL calls in to NICS to run a background check for your gun purchase, those people who answer the calls are call-center contractors too. Your dealer talks to a real agent when they transfer the call for "further review".