I don't see any contradiction about Carrey having armed security guards and being anti-NRA.
Security guards have guns in a law-enforcement capacity, and they've been psychologically checked so they won't go off on crazy gun rampages.
It's different from people taking issue with the fact the NRA wants to give US civilians access to the sort of firepower other First World nations restrict to the Military.
Very true. I own and drive a car, so does this mean I have to approve of driving without a licence, or like Top Gear?
The NRA like to give the impression that they represent all gun owners, and all decent people (who being decent should want to own a gun), but in reality their campaigning protects the businesses of gun manufacturers and people who want to own un-traceable guns.
Don't get me wrong, I'm not confident that all security guards/police officers are mentally stable, or that their background checks will be sufficient, but then I don't presume that everyone with a driving licence will always drive safely.
Within the whole gun debate their are many shades of grey, especially in country like America where guns are already rife. You don't have to believe in a total gun ban if you don't want a gun free for all.