What will she come up with next?
She strikes me as being the type that spends all her working hours scouring the news reports, political situations, gun manufacturers websites, and maybe even forums like this one, looking for opportunities to turn a 'nothing' into a 'something' and thus stick another feather in her cap no matter how it turns out.
For example, by raising a concern over .50's being used to kill border patrol agents from across the border at long range, she can use this to either chalk up another victory for gun control, or just make herself look like she's right, or both.
If she's able to push this far enough and end up getting the manufacture of .50's prohibited in this country, she claims a victory for gun control.
If, on the other hand, it doesn't work and nothing is done, and then a border patrol agent is shot at from across the border with a .50 (a fatality isn't even necesssary, just being shot at will do) by the Mexican military, drug smugglers, or anyone else, then she can say "See, I told you so."
In her mind, she can't lose either way.
She may be misguided and just plain ignorant, but she's also a shrewd, conniving little would-be dictator.