There's a lot of lowbrow, bad B-movie entertainment value to be had in "Reign of Fire," a post-Apocalyptic dragon slayer flick in which the two leads chomp considerably more scenery with their acting than fire-breathing monsters barbecue with their breath.

This overacting is clearly by design since the film stars Christian Bale and Matthew McConaughey, two talented actors more than capable of subtly and nuance. But subtly and nuance have no place in a movie about the remnants of humanity battling dragons for dominance over Earth, and director Rob Bowman knows it.

Buffed and sweaty Bale ("Captain Corelli's Mandolin," "American Psycho") emotes in the extreme as the gruff but benevolent leader of a rag-tag community that survives in an ancient castle outside London (a nod to dragon tales of yore), which they've turned into a fortress. The year is 2020, and 18 years before Bale was the little boy who unwittingly discovered and awoke the alpha dragon in an underground cavity while visiting his construction forewoman mom on a subway tunnel job.

The film provides an abbreviated history lesson -- the dragons repopulated at a rate of a million in a year and scorched the earth despite man's best efforts to destroy them -- which is intended to go by so fast that you don't have time to think about the nonsense of it all. (How did they repopulate from only one dragon? Why was that one dragon in hibernation under London to begin with? How long had it been there?)

Then with the arrival of McConaughey comes the action. Muscle-bound, heavily tattooed and scruffily bearded but shaved tough-guy bald on top, he's a gravely voiced mad-dog ex-Marine leading his own private battalion of dragon-killers on the warpath. Arriving at Bale's fortress in a convoy of tanks, his small army is first mistaken for marauders, until their helicopter flies over. It's the first airplane of any kind that these survivors have seen since the dragons took over the earth and sky, and their sense of awe is so palpable you a tingle right along with them when it swoops into the castle compound.

These daredevils have a complex and amazing system for killing dragons that includes computer triangulation (high technology has survived in bits and pieces), using sky divers as bait, launching chain mail nets that impair the beasts' wings, then dramatically harpooning the gigantic gargoyles to bring them down. Their first action-packed on-screen kill is unquestionably the highlight of the movie.

They're on their way to London because they've deduced that's where they can find the one male dragon that -- suspension of disbelief warning! -- fertilizes all the dragon eggs in the world. If they can kill it, the dragons will die out and the humans win. But they've stopped by Bale's community because they need new recruits for the final battle.

Long story short, all McConaughey's troops get cooked (literally!) in their clash with the beast, leaving just Bale and hottie helicopter pilot Izabella Scorupco ("Vertical Limit," "GoldenEye") to help him take the big boy down.

The movie's dragon battle scenes, while largely typical of rubble-strewn-future action flicks, are contagiously energetic and cheer-worthy, and the dragons themselves are such spectacularly realistic CGI creations that it didn't even occurred to me until a day later just how packed the movie was with special effects.

Make no mistake, though -- being pure B-movie, "Reign of Fire" is also over-stuffed with lame dialogue ("We're outnumbered hundreds to three!"), lose ends and plot holes (if the dragons "can see even better by night" why do the human warriors travel by night?), silly, heat-sensing Dragon-Vision camera shots, and a generous helping of cinematic ham.

Determined not to be upstaged by a fire-breathing special effect, both Bale and McConaughey seem to delight in battling each other for the over-acting crown, bugging out their eyes as they barking their lines in affected raspy-rugged whispers. Being the kind of guy who rides atop his tank straddling the machine gun, McConaughey wins this battle, hands down. The moment he spits his cigar stub on the ground and hollers, "Lock and load!" you know he loves the smell of brimstone in the morning.