The production lacks the power to unsettle despite a fine cast of killers and wannabes who changed, or at least made, history gunning for presidents.The one reliably blood-chilling moment in Stephen Sondheim and John Weidman’s “Assassins” comes courtesy of a killer who is, at best, a footnote in American history: Charles J. Guiteau, the lawyer who shot President James A. Garfield in 1881.Guiteau aims his gun at the audience, panning over us slowly, deliberately, in tension-filled silence. The music is stopped. The menace is visceral.“Facing the barrel of a gun, even when it’s just in a musical, is the kind of shock that can exist only in live theater,” Sondheim wrote in his 2011 book “Look, I Made a Hat,” in which he called this lingering, life-or-death moment in “Assassins” his favorite in a show rife with gun-waving murderers and murderers manqué.I’d wondered how that confrontation would land in John Doyle’s current revival at Classic Stage Company, not so much because of the state of our armed-to-the-teeth nation but because of the shooting last month on the set of the Alec Baldwin film “Rust,” where a real gun fired a real bullet that killed a real person, when it was all meant to be pretend.The surprising answer is that it doesn’t land at all, because Doyle has defanged the moment, speeding it up to a manic pace. His jittery Guiteau, played by a creepily unnerving Will Swenson, swings the gun left, right and center so fast that there’s no time for us to feel endangered, no time for the threat to lodge inside us and turn to fear.Granted, maybe we’re all too freaked out right now anyway to have a prop gun pointed at us. But I wish that Doyle had plastered the lobby with unmissable posters explaining, as the digital program does, that the show’s guns “are replicas that were provided, checked, and rendered inoperable” by a weapons specialist. I wish he’d had leaflets printed with the same message, and handed to each person on the way in.I wish he’d kept that long, scary moment. Because racing through it undermines the potency of the show, Classic Stage’s first since the shutdown.Even with a powerhouse cast, this stripped down, off-balance production — originally slated for spring 2020 as part of the Sondheim 90th-birthday festivities — never does find a way to make the audience feel the stakes of its characters’ actions. That’s true whether we view the assassins purely as historical figures or also as metaphors for an aggressive strain of lethal discontent as American as Old Glory.From left: Tavi Gevinson, Kuhn, Will Swenson, Uranowitz, Andy Grotelueschen, Adam Chanler-Berat, Wesley Taylor and Pasquale.Sara Krulwich/The New York TimesThe show’s vaudevillian patchwork of stories about volatile 19th- and 20th-century misfits who murdered a president, or tried to, makes us laugh and leaves us humming. But we are ultimately unperturbed.And maybe that, too, is a sign of the times: that we have lately lived through such virulent, brutal threats to our democracy that this motley bunch (John Wilkes Booth! Lee Harvey Oswald! Lynette (Squeaky) Fromme!) hardly seems ominous. What risk they posed, what damage they did, is past.But there are also plenty of parallels to the present in Sondheim’s sharp-eyed song cycle of the ostensibly dispossessed and in Weidman’s often casually violent dialogue. Doyle, a Sondheim veteran who staged the 2017 revival of the Sondheim-Weidman “Pacific Overtures,” infers one contemporary correlation outright with his final stage image, which I will not spoil.“No one can be put in jail for his dreams,” Booth — the alpha assassin, played by Steven Pasquale as a smooth Southern shark — sings to the others in the delusion-packed opening number, “Everybody’s Got the Right.”Gathered at a fairground shooting gallery, they are encouraged to kill a president to win a prize. On Doyle’s set, above a bare thrust stage painted with the Stars and Stripes, a giant round target flashes with projections (by Steve Channon) of the various presidents’ faces.That same screen, bordered with lights that shine red, blue and — peculiarly — not white but pale yellow, is pretty much all the scenery the show gets, which is in keeping with Doyle’s pared-back aesthetic. But the storytelling would have benefited from more visual cues. Many projections are too coldly literal and too far removed from the action to aid it properly.When Giuseppe Zangara (Wesley Taylor), the would-be assassin of Franklin D. Roosevelt, is executed, an image of an electric chair is projected above him. When Guiteau ascends to the gallows for his hanging while singing, with increasing franticness, “I am going to the Lordy, I am so glad,” Swenson has no stairs to dance on; there’s merely a distant projection of an empty noose.From left, Swenson, Rob Morrison (rear) and Ethan Slater.Sara Krulwich/The New York TimesSimilarly, when Booth is in hiding, having shot Lincoln, there is no visual indication that he himself is injured, his leg broken. Pasquale is darkly charismatic, though: singing softly, beguilingly of “blood on the clover” from the Civil War in “The Ballad of Booth,” before the mask of romance slips and he spits a racist slur about Lincoln at venomous volume.The three-piece orchestra, led by Greg Jarrett, is supplemented in trademark Doyle style by some of the cast, notably Ethan Slater as the appealing Balladeer, who strolls the stage in a blue jumpsuit, playing an acoustic guitar. (Costumes are by Ann Hould-Ward.) Later he transforms into Oswald, a despondent young man with a powerful gun that — like many things here — comes wrapped in the flag.Heretical as it sounds, comic dialogue, not song, is this production’s strongest suit. But aside from a curiously underwhelming rendition of “Unworthy of Your Love,” the pretty, poppy duet between Fromme (Tavi Gevinson) and John Hinckley Jr. (Adam Chanler-Berat, who is suitably skin-crawling as the man who attempted to assassinate Ronald Reagan in 1981), it’s not that the musical performances are lacking.It’s that the lighter book scenes really shine, especially the hilariously mercurial ramblings of the wannabe Richard Nixon killer Samuel Byck (Andy Grotelueschen) and the terrifically lively scenes between Gerald Ford’s foiled assassins, Fromme and Sara Jane Moore (Judy Kuhn, handily transcending the role’s scatterbrained-broad stereotype).“Assassins” has been faulted since its premiere three decades ago for a supposed failure to make its disparate parts cohere. It’s also proved many times that they can, yet Doyle’s staging never manages to harness that cumulative power. Faithful though it is to the show’s sung and spoken text, it’s missing some vital connective tissue.Of course, the same could be said of the country. This is a musical with a deep, warning sense of something frighteningly wrong in the fabric of the United States — a nation where, as the song goes, “Something just broke.”You can still hear that alarm in this production. But don’t expect to feel it more than distantly.AssassinsThrough Jan. 29 at Classic Stage Company, Manhattan; classicstage.org. Running time: 1 hour 45 minutes. More