Does heroism translate from real-life to the big screen?

Not really, as it turns out. Oh sure, Johnny Weismuller was an Olympic hero – and he turned that into big-screen career playing Tarzan. On the other hand, Audie Murphy, a real-life World War II hero, played a civil-war soldier wrestling with questions of his own bravery in “Red Badge of Courage,” and himself in “To Hell and Back,” but his movie career was not unlike that of pro-wrestling hero Hulk Hogan in both duration and quality of output.

In other words, just because you played the part in real life doesn’t mean you can do it on the big screen. Nor, probably, should you.

These thoughts came to mind while watching “Act of Valor,” a film where casting is supposed to somehow enhance the experience of watching an otherwise quite-ordinary rescue-mission military-action film.

The casting: real-life Navy SEALs, the true bad-ass commandoes from the front lines, acting out what supposedly is a fictionalized version of one of their many missions.

Instead of adding to the film, however, the casting makes it a little like watching the second-unit on any fairly proficient big-budget action film. You’ve got a squad full of faceless stuntmen, acting like they know what they’re doing.

These guys aren’t actors, however, and so they bring nothing else to the already underwritten roles of men in combat: hard-bitten and tough in action, wise-cracking when they’re kicking back. They’re not characters: They’re character types. It’s like watching “The Expendables,” without all the plastic surgery.

The plot itself feels as generic as a History Channel reenactment, involving arms deals, terrorists, a kidnapped undercover agent – and, of course, the ass-kicking SEALs, who do their work with quiet assurance and a noteworthy lack of bravado.

At least it’s not in 3D.