Guns N’ Roses is once more a fabulous rock-and-roll band, no longer the bloated and spent combo it was upon breaking up nearly a quarter-century ago. For the Not in This Lifetime tour, which stopped by FedEx Field on Sunday night, the majority of GNR’s key original members were back together and proved there can be power in a reunion.

In their late-’80s/early-’90s heyday, GNR was regarded as the world’s most dangerous band and had a reputation for starting shows obnoxiously late or ending them obnoxiously early. But Sunday’s gig started on time, and throughout its 2½ hours, all the banter from the once predictably unpredictable frontman Axl Rose, now 54, was about how nice the weather was and how much fun he was having. He showed that he had nicely recovered from a broken foot that kept him confined to a chair during the band’s high-profile Coachella performances in April, running to a perch above and behind the drum riser to shriek the chorus to “Welcome to the Jungle.” He did his trademark snakey slither across the stage just like old times whenever the spirit moved him. And his once-fragile voice never wavered; in fact, it seems rangier than ever, as he confidently crooned through crowd-fave power ballads “Patience” and “November Rain.”

This reunion tour isn’t all about Axl, though. During GNR’s hateful hiatus, Rose brought in a rotating cast of guitarists trying to fill Slash’s top hat, most notably Buckethead (nee Brian Patrick Carroll), who wore a KFC tub on his noggin as he played. The sub in the high-cholesterol headgear never made fans forget GNR’s original axman, however. One of the crowd’s biggest roars — and this night was full of ’em — came early in the show during “Mr. Brownstone,” as Slash took the spotlight with his first big solo of the night while holding his Les Paul in front of him and up high, like a golfer would a championship trophy.

Now 50, Slash was decked out in leather pants, cool-kid sneakers and a cutoff T-shirt, with those overgrown locks obscuring almost everything about his face other than a nose ring. In other words, his current ensemble was exactly like his old one, save the cigarette that once was as much a part of his face as his nose. He can still play super smooth, as he did for “The Godfather Theme,” or fast, as during the solo on “Double Talkin’ Jive.” Slash was so juiced to be back in the fold that he even stood front and center while playing the power chords that drive “Chinese Democracy,” the title tune of an album released in 2008 after Axl spent about a decade and a reported $13 million-plus to make it without his mates.

Duff McKagan, the bassist who was replaced by a Replacement (Tommy Stinson) during the estranged days, took over the show at one point to cover Iggy and the Stooges’ “Raw Power,” which GNR had recorded for 1993’s collection, “The Spaghetti Incident.” McKagan, 52, had a Prince logo stenciled on his bass and looks alarmingly like David Bowie these days. He rocked Iggy’s punk nugget hard and sounded great, but the crowd did not seem as moved as much as the performance warranted.

Other covers that didn’t quite click included “The Seeker” by the Who and instrumental versions of Derek and the Dominos’ “Layla” and Pink Floyd’s “Wish You Were Here.”

The predictable GNR covers, however, were embraced with glee by the crowd that filled the lower tiers of the huge stadium. During Paul McCartney and Wings’ “Live and Let Die,” Slash worked in an impressive stage leap for a guy his age, while Axl ended the tune with his best “The Shining”-era Jack Nicholson scowl and a shriek that seemed capable of breaking glass. For Bob Dylan’s “Knockin’ on Heaven’s Door,” Slash shredded on a double-neck guitar, and a massive airplane flew low and slow over the stadium while the crowd screamed the chorus, making the moment almost impossibly bombastic.

When fireworks were launched during the final bars of the set-closing “Paradise City,” it was nearly midnight, yet the guys onstage looked at least as ready to keep rocking as the fans, who couldn’t have cheered harder. This was a show so fabulous that witnesses could rightly wish that GNR’s reunited mates don’t end the Not in This Lifetime tour till death do they part.