The most impressive thing about “The Expendables 3” is the degree of cynical arrogance it must have taken to release it. So much star power packed together in one place hasn’t produced such a cheesy result since the recording of “We Are the World.”

This time around, the mercenary band of noble thugs led by Barney Ross (“Expendables” creator Sylvester Stallone) faces off against arms trader Conrad Stonebanks (Mel Gibson), an ex-Expendable gone rogue. To give his crew an extra edge, Barney decides to bring in some techno-literate whippersnappers to help defeat his old foe (whose surname is the most subtle thing about the movie).

Gunplay and explosions spin from Mogadishu to Moscow to Vegas to New York, although the locations often look suspiciously like the same set hastily redressed. Yet the nonstop action rarely sparks suspense. The only time you’re on the edge of your seat is when Stallone tries to speak — all that face work seems to have given him a permanent case of lockjaw.

Instead of bringing in more depth, humor or at least nostalgic appreciation, the former A-list codgers brought in presumably to bolster the moronic script might as well be reading from cue cards. Harrison Ford, as CIA black-ops commissioner Drummer, utters his lines as though he just popped a couple of Excedrin PMs. Kelsey Grammer, Robert Davi and Arnold Schwarzenegger are all in lazy drive-by mode, their minds more likely occupied by what they’re going to have for dinner.

The cast is crammed with too many boldfaced names given too little to do, especially Wesley Snipes, whose shining art-imitates-life moment comes when he says he was in prison for tax evasion.

Schwarzenegger got the biggest laughs from a preview audience for saying, “Look out for the chop-pah!” and “Get in the chop-pah!” Arnold, you’ve lived in the States more than 40 years — you can start pronouncing your R’s any day now. On the other hand, moments such as this transcend into high camp, which might be the most enjoyable way to approach the movie.

The new blood, even smoldering Kellan Lutz, adds little spark to the dull proceedings. Instead, returning cast members Antonio Banderas as the hilariously garrulous Galgo and Jason Statham as all-around hunk Lee Christmas are the only guys lifting more than a pinky’s worth of acting effort.

“You’re only old when you surrender,” Galgo tells Barney. No doubt, but it’s past time for this stale vanity project to wave the white flag.