Following a recording session, he wrote "Shotgun Willie"—the song that would become the title track of the album—on the empty packaging of a sanitary napkin while in the bathroom of his hotel room.

In spite of poor sales, Shotgun Willie received good reviews and gained Nelson major recognition with younger audiences.

The recording was one of the first albums of outlaw country—a new subgenre of country music and an alternative to the conservative restrictions of the Nashville sound, the dominant style in the genre at the time.

Nelson's manager, Neil Reshen, negotiated an agreement with RCA Records to end the contract upon return of US$1,400 that the singer had been overpaid.

[3] Nelson had felt creatively hamstrung by RCA's strict recording practices and frustrated at not being permitted to use his touring band in the studio.

Another guest was Atlantic Records vice-president Jerry Wexler, who previously had produced works for artists such as Ray Charles and Aretha Franklin.

[7] Pacing in his hotel room, he went to the bathroom, where he sat on the toilet and took the empty envelope from a sanitary napkin from the sink, and penned the song on that.

[12] The title of the song refers to the nickname Nelson received after his daughter, Susie, warned him of the domestic abuse suffered by her sister Lana.

Nelson drove to Lana's house, where he fought with her husband Steve Warren, and threatened to kill him if he repeated the assault.

[18] In his biographical book about Nelson, Joe Nick Patoski noted that the recording of the album "was sloppy and chaotic, technically and artistically uneven, with horns and strings occasionally bumping up against the musical core of Bee Spears, Paul English, Bobbie Nelson, Jimmy Day, and Willie...The music was more country than what was being played on the radio but somehow different.

Beyond the mystery, though, I heard that his musical roots and mine were the same: Hank Williams, Bob Wills, country black blues..."[21] Nelson later declared that with Wexler's producing he "cranked out songs, one after the other" and that "the atmosphere was right".

Ed Ward from Creem later commented: "I'd underestimated the professionalism of all concerned, not to mention the core ensemble of musicians themselves, who decided to test the sound of the studio with a spirited version of 'Under the Double Eagle,' which left me awestruck: Willie wasn't only a great songwriter, he was a goddamn virtuoso on that battered Martin guitar of his!

[24] The recording led the singer to a new style; he later stated regarding his new musical identity that Shotgun Willie had "cleared his throat.

[31] Robert Christgau wrote: "This attempt to turn Nelson into a star runs into trouble when it induces him to outshout Memphis horns or Western swing.

He's the same old Willie, but veteran producer Jerry Wexler finally captured on wax the energy Nelson projects in person".

Critic Bill McAllister mentioned the support that Texas Longhorns football coach Darrell Royal gave Nelson and his music.

[35] The Arizona Republic presented Nelson as "an accomplished baritone and composer", as the publication appealed the readers to "lend old Shotgun an ear and find out what C&W music sounds like when it's not sung through the nose, or hat".

"[38] School Library Journal wrote: "Willie Nelson differs (from) rock artists framing their music with a country & western façade — in that he appears a honky-tonk stardust cowboy to the core.

This album abounds in unabashed sentimentalism, nasal singing, lyrics preoccupied with booze, religion, and love gone bad, and stereotyped Nashville instrumentation (twangy steel guitars, fiddles, and a clean rhythm section characterized by the minimal use of bass drum and cymbals, both of which gain heavy mileage with rock performers).

This is laid-back, deceptively complex music, equal parts country, rock attitude, jazz musicianship, and troubadour storytelling".