LAS VEGAS — Two singers, two gigs, two cities and stages, the same opening song. "It's not my imagination," it begins, drawled. Pause, and then a yell: "I've got a gun at my back!"
The first version, on a recent Saturday night at the Korova club in San Antonio, was Ron Reyes': a rallying cry. The second, the following Monday night at an outdoor stage of the Punk Rock Bowling and Music Festival in Las Vegas, was Keith Morris': a freaked howl. Morris was the first singer, and Reyes the second, of Black Flag, which started in the late '70s and went on to become one of America's most important punk bands, its four-bars logo tattooed on 18- to 50-year-old flesh all over the world.
The song was Revenge, from Black Flag's second EP, released in 1980. The elasticity of the vowels in imagination — by both singers — is South Bay Los Angeles. The gun in the narrative isn't explicitly, but could be, a cop's; punks were new and little understood on the West Coast when Black Flag started, and hunted by the local police. Shows were stopped regularly; violence followed the band; little money was made.
Until its end in 1986, Black Flag went through at least 16 band members. The fourth and final singer was Henry Rollins, the most famous member of the band, then and since. But final is perhaps the wrong word. Two reunionlike post-Black Flag entities are on tour now. Reyes is in one called Black Flag; Morris is in one called Flag. Neither includes Rollins, who has more or less given up music for writing. Both bands — for reunion bands — are strangely good and in possession of a life force, in different ways.
Black Flag, the one with Reyes, will play Wednesday at Buster's Billiards & Backroom in Lexington and Thursday in Newport.
The dueling-reunions aspect came together quickly. In late 2011, Morris convened a few of the band's most significant ex-members — bassist Chuck Dukowski and drummer Bill Stevenson, and Stephen Egerton, guitarist for the Descendents — for a one-off set, and it went well. They started planning, and had a tour almost ready to announce in January this year.
But Greg Ginn, Black Flag's lead guitarist, principal songwriter and owner of its old record label, SST, beat them to it, announcing that a new Black Flag — he has legal rights to the name — would play at the Hevy Music Festival in England. Flag rushed to announce its own tour on the same day. Ginn followed with more news, of a plan to tour roughly the same markets at about the same time as Flag (although Flag isn't playing near Lexington), and to release an album of new songs.
Four months later, the Black Flag show in San Antonio was the third in the United States after a weeklong warm-up in Europe; the Flag concert in Vegas was its first in this country after an unannounced gig at the Moose Lodge in Redondo Beach, Calif. — the site, in fact, of Black Flag's first gig in 1979 — and three dates in Europe.
There is some tension between the two groups. Several former members of Black Flag don't talk to Ginn anymore; as the band's musical director, more or less, he fired a lot of them or made it hard for them to stay.
But the members of Flag say their band is not about getting back at Ginn. Morris, in a brief conversation before Flag's set in Las Vegas, put Flag's existence as a basic declaration of identity: The core of Black Flag came from the same square mile of Hermosa Beach, Calif.
Ginn, for his part, seems not to be warm about Flag. The official site for Black Flag refers to Flag as "the 'fake' Flag band playing the old songs of Black Flag in an embarrassingly weak 'mailing it in' fashion."
At the moment, if you're a journalist, neither he nor Reyes is talking to you.
What was Black Flag? A lot of it boils down to Ginn, the un-guitar hero. His sound was untutored, inexact, viscid and full of scrabbling solos, delivered with force and wobbly relation to the beat. He was the prime agent for the group's change, in 1983, toward slower tempos, turning toward a kind of free-improvisation doom metal. (He's into electronic music and jam bands now; in San Antonio he wore a T-shirt with the logo of Camp Bisco, the annual festival of the jam band the Disco Biscuits.)
At the Black Flag show, Ginn's levels of guitar and theremin — which he also plays now, for what it's worth — were pushed so high that they nearly blotted out his adequate band. (The rhythm section is recent-hire bassist Dave Klein and drummer Gregory Moore, who's been in some of Ginn's other groups for 20 years.) They leaned toward old songs, from 1979 to 1981, but also pushed toward the later mid-tempo music; they also played several songs from the forthcoming new album, which are slight and dull, and made you realize how good the writing was in early Black Flag.
But the best part — besides Reyes' gung-ho effort not to be flattened by guitar — was that Ginn does not quote himself as an improviser. All his solos were from scratch, and scratchy. He's unpredictable, inconsistent, maddening and exciting; for a while he'd lose focus and grow slack and dull, then snap back into focus and attack the music again.
The two sets had 10 songs in common. But Flag's show in Las Vegas seemed qualitatively different. This is a complete band; all parts are equal. Stevenson's drumming was crisp and powerful; he was borrowing style from Roberto Velverde, aka Robo, a Colombian musician two drummers before him in the band, who put cumbia rhythm into his high-hat patterns and made punk swing. Dukowski played rushing, impatient, vivid bass; Egerton, using the same kind of guitar Ginn used to play in the '80s, a clear-body Ampeg Dan Armstrong, replicated some of Ginn's old solos, more precisely than Ginn ever did. (This can be troubling: Here is where Flag does, to an extent, resemble a cover band, engineered to please.)
And Morris, now with long dreadlocks, small and wary, smart-alecky and comical, kept control.
"I hope you're having fun," he told the audience, as earnest as he can sound. "When we started doing this, that wasn't a possibility."
■ 9 p.m. June 19. Buster's Billiards & Backroom, 899 Manchester St., Lexington. $25, $28. Available at (859) 368-8871 or Bustersbb.com.
■ 8 p.m. June 20. Southgate House Revival, 111 E. Sixth St., Newport. $30, $35. (859) 431-2201. Southgatehouse.com.