Can someone that is only reserves be a drill sgt in any branch?
Yes. In the Army there are several Reserve Traning Units that consist primarily of Drill Sergeants. Their mission has historically been to provide a trained cadre of instructors (Drill Sergeants) in the event of the declaration of general war when training requirements would overwhelm the current training pipeline (draft). To keep them current, they usually spend their Annual Training Cycle in support of a BCT unit. Examples of these units are the 95th and 104th Division (Institutional Training). There are even two Drill Sergeants of the Year annually selected by the Army. One is Active Component, and the other Reserve. As a side note, you will occassionally see a “Drill Private” out in the force. This is the often the result of a Reserve Drill Sergeant who decides to go active duty and takes a bust in grade to do it. They went to Drill Sergeant school as a Reservist NCO and thus are authorized the D.S. Identification Badge, but end up on active duty as a PFC. It has always cracked me
