The second album by Bushman’s Revenge, Jitterbug (Rune Grammofon), includes two tracks that should be all the sales pitch you need to decide if the instrumental trio’s heavy, improvised and often rhythmically-free rock is right for you. The first 10 minutes of the record, with the Yoda-speak title “Always in Motion the Future Is,” is guitarist Even Helte Hermansen (also in the Norwegian jazz-metal ensemble Shining) spinning out, in tangled swirls and long free falls fattened with distortion, like Jimi Hendrix in “Machine Gun” but cut free of straight time. Bassist Rune Nergaard and drummer Gard Nilssen chase Hermansen’s impulses as if Jitterbug was a Marshall-amp version of John Coltrane’s Interstellar Space. Then there is the Motörhead cover, “Damage Case,” which comes without the lyrics (the band dubs this a “happy go lucky karaoke version” — get the words and try it yourself). Everything proceeds according to the original until a minute and a half in, when the Revenge take off for twenty seconds of no-beat-or-chord-change blowout, from which they swing back, on their idea of a dime, into the main hook. It’s all over in three minutes, but it’s enough to reassure that everything here (like the battered blues with organist Ståle Stroløkken, “While My Guitar Gently Breaks,” and the dark march “Personal Poltergeist”) is rock first, made with fierce proficient connection — then free flight.