Thank you all.

I was going mad trying to remember all the lyrics, and finally located this site, which seems to be the only place that has this information.

Except for variations like "Old buddy" instead of gunslinger, here's how I now have the song (with "brothers" updated to "siblings"):

Gunslinger, gunslinger, where did you go wrong?
When you were a child, did the Cheyenne and Sioux
Refuse to play nicely with you?
Did you always feel you didn't belong?
Gunslinger.

Gunslinger, gunslinger, why do you act so strange?
When you were a child were you forced to compete
With siblings you never could beat
Did you come from a broken home on the range?
Gunslinger.

Gunslinger, gunslinger, please take my advice.
You know in your mind that you're plumb insecure,
That killin' a man is real immature.
It is just an attention-getting device.
Gunslinger.

You've killed one hundred and thirty men, my darling.
And now you want to settle down.
But other gunslingers are a-gunnin' for you,
And a man's gotta do what a man's gotta do.
Gunslinger.

Don't wear your guns to town tonight, gunslinger.
Last night you cried out "Mother dear!"
You've got a recurrent dream in your craw
And that dream of your maw will inhibit your draw.
Gunslinger.

There you lie dead in the dust, gunslinger
And now your myth begins.
Out in the west, the folks all believe
You faced and killed the toughest hombres of your day
But time has exposed your feet of clay.
Current researchers have clearly shown
That 93.6% of the gunmen you killed were simply accident-prone.

Gunslinger.