Both of Memphis punk band Ex-Cult’s albums contained at least one song that neared the six-minute mark, whether it was to provide a platform for stretches of tangential rock ‘n’ roll solos (“Future Victims”) or clatters of screeching guitars and manic, unrelenting drumming (“Catholic Entries”). On their upcoming EP, “Cigarette Machine” may be that outlier. More refined drum fills provide structure for when the sturdy ‘70s punk riffs swerve into semi-psychedelic territory. These unhinged digressions serve a purpose, though: to rip the mid-tempo pace to shreds. But they’re sure to pause and let scrappy feedback writhe in the wake of Chris Shaw’s seething vocals that still bludgeon as venomously as ever. Yet it’s when heaving gang vocals blast through a throbbing chord progression that “Cigarette Machine” most urgently threatens to combust.