The recording of this song is in the key E minor,
for most of the song is jumps between the
Em and an F#dim, as so:

Em (022000@1)             F#dim (2312xx@1)                 Be(7)------7x-----|(8)-------------| (x2444x@1)     |7----7----|7----7----|
B(8)------8x-----|(10)-----10~~~~~|      |7----7----|7----7----|
G(9)------9x-----|(11)---------11~|  x4  |8----8----|8----8----|o
D(9)------9x-----|(10)------------|  /    |9----9----|9----9----|o
A-7~~~~~~~~x-----|(9)--9~~~~~~~~~~| /     |9----9----|9----9----|
E----------------|----------------|/      |7----7----|7----7----|
  Go                           Tell...     Gun      
                                        
  A (x02220@1)     B (x2444x@1)      Em (022000@1)    C (x32010@1)           
E-5-------7------|-7-------3------|
B-5-------7------|(8)-----(5)-----| 
G(6)-----(8)-----|-9-------5------|  x4
D-7-------9------|-9-------5------|  /
A-7-------9------|-7-------3------| /
E-5-------7------|-7-------3------|/
 look-   sky      Tricks   mind
   ing     plays     on
    at               your 
      the

The Greenhornes