Ironically, it is quite easy for any person to obtain an AK-47 in many third world countries. They don't need to attend US gun shows, where they could only get a semi-auto version. Fully automatic AK-47s have proliferated throughout the third world, as they are cheap and easy to make. Obviously she didn't bother checking the facts concerning her statements.
As far as OTHER types of weapons that the Afghanis may have obtained from US sources, gee, I wonder where the Afghanis got their Stinger missiles from? If Sarah Brady thinks that they must have attended a gun show here in America so that they can purchase those Stinger missiles, she may be right. It was a gun show in Washington DC put on by the US Government just for them. And they didn't even have to pay for those missiles, they were given to them free courtesy of US taxpayers.
As far as terrorism is concerned, she must have forgotten to ask for background checks at all stores that sell box cutters, as that was the weapon of choice for those who destroyed the World Trade Center.
The real 'weapon' the terrorists had was the liberal 'give hijackers that they want' philosophy embraced by the passengers and crew of three of those flights. Fortunately, that weapon has been completely and utterly destroyed, hopefully forever.