Height, weight, gender? That’s all irrelevant. Someone with basic self defense skills can’t perform a gun disarm.
What the shooter wants also doesn’t really matter. Obviously, if they’re going to shoot someone anyway, then trying to grab their gun isn’t going to make things worse. But, if they weren’t planning to shoot someone, you’re going to force them to try anyway.
You can think of it like shoving your hand into a running garbage disposal, the gun itself is the dangerous thing, but in attempting the disarm you are the one engaging in the dangerous activity.
Short version; you have a character who brandished a gun to feel like a big man, and your character tried to play hero, getting people, and possibly herself, killed in the process.
To quote Spock from Star Trek, “what you want is irrelevant; what you’ve chosen is at hand.”
So, no. With basic training, the only thing she can do is make the situation worse.