Gun-in-movie question: The Rock

[FNFiveSeven]

Near the end of the movie, "the rock," one of the badguys tries to take out Nic Cage with a scoped out rifle of some sort. I can't tell exactly which one it is, but it *seems* to be an LAR grizzley (50 BMG!). Is this possible? I didn't think this rifle existed when the movie was filmed... but the selector/trigger and butt-plate look identical to the Grizzly 50. Thanks in advance for any help solving this small mistery,

-Robert