On March 1, 1965, Capitol Records released I’ve Got A Tiger By The Tail, Buck’s ninth LP. It featured the title track, "Cryin’ Time," the cowboy favorite "Streets of Laredo," Bob Wills "A Maiden’s Prayer," and a rocking version of Chuck Berry’s rock’n’roll classic "Memphis." Ironically, the March 1965 issue of the Nashville-based fan magazine Music City News carried a paid ad from Buck. In his "Pledge to Country Music," he stated,

I Shall Sing No Song That Is Not A Country Song. I Shall Make No Record That Is Not A Country Record. I Refuse To Be Known As Anything But A Country Singer. I am Proud To Be Associated With Country Music. Country Music And Country Music Fans Made Me What I Am Today. And I Shall Not Forget It.

Some fans felt he broke this pledge by recording "Memphis," and, later, The Coasters’ "Charlie Brown" and his hit version of Chuck Berry’s "Johnny B. Goode." However, in his own mind, Buck had made a subtle musical distinction most fans didn’t notice, particularly regarding the Chuck Berry songs.

"I see ‘Memphis’ as bein’ rockabilly," he says. "I didn’t say I wasn’t gonna do rockabilly. I just said I ain’t gonna sing no song that ain’t a country song. I won’t be know as anything but a country singer. I meant that, I still mean that. Listen to the lyrics. If they’re not country lyrics...the melody...if that ain’t a country melody...The only thing was, a black man was singin’ it, a black man who I was a big fan of. So, my famous saying for my little pledge - I didn’t date it. I really meant it at the time. I don’t mean for it to be taken lightly."