Since automatic weapons have long been banned, and bad guys as well as good guys use semiautomatics, gun control fanatics watching this film might be inspired to renew their efforts to ban magazines over x capacity.
They would be even more happier trying to ban semiautomatics since that would take away the majority of guns for everyone -- if only the bad guys would follow the rules, which they never do.
Bad guys as well as good guys realize that in most situations selective fire from semiautomatic weapons is more effective than spraying with automatic weapons. If bad guys thought automatics were best for them, they'd find ways to get and use them.
While helpful to general understanding, this film emphasizing how assault rifles and sporting rifles often share the same actions potentially could backfire by giving gun control zealots more ammo.