Who is "Shotgun Joe?" And where is he going with that gun in his hand? What gun? Why do they call him "Shotgun Joe?" I do not want to speculate anything because from the little research that I did, this tune could refer to a few different people, or possibly a controversial incident. Unless I read some definitive documentation, I am just going to have to wonder about the history of this tune. UPDATE: Here's some reading material from Home Of The Groove (scroll down to "The First Indian / Brass Showdown / Throwdown?").
When I was playing in a mediocre brass band for a brief period, we had a joke before we played every tune. Someone would ask, "What key is this one in?" Someone else would inevitably reply, "Brass Band flat." Hardy har-har! It is funny because it is true… I guess. If you trace back the European history of brass bands, most of the music is written in the keys of Bb or Eb based on how the horns physically resonate. As modern composers arranged more hip sounding tunes for brass band, the common keys would expand to some of the relatives of Bb or Eb. Thus, we have "Shotgun Joe" in the key of E minor, which can add some variety to a long night of brass band music.
Yet, for the trombone, E minor can be a deceptive key depending on the octave in which you play. Above middle C, the Em scale lays out pretty well, all within the first three slide positions. It requires little physical movement to jump around the scale and the partials of the horn. But take that all down an octave, like this solo for "Shotgun Joe," and it becomes a whole different ballgame. The slide gets caught in "no-man's-land" between second and fourth position, and it involves constant movement. Besides the physical demands of this octave range, the tone of the trombone sounds muddy and tends to get lost when playing in a band. So try to take this solo up an octave so that it stands out from the rest of the crowd.
Judging from this recording, I assume that the trombonist's chops may have been tired which may have affected his playing ability, and had to settle for a low octave solo. It happens. But it is usually the result of tired lung muscles that struggle with producing a constant stream of air. One thing you can try is to play this solo in a legato style, and focus on filling the horn with air. If you can develop the air to play it elegantly, you can then add on the original staccato styling, and even then light up the horn in the higher octave with ease.
Well, here's a YouTube video that shines a little light on the history of this tune.
Recommended Reading: Home Of The Groove blog by Dan Phillips.