Heard of this thing called point-blank range? Here, I'll Wikipedia it.
In forensics and popular usage, point-blank range has come to mean extreme close range (i.e., target within about a meter (3 feet) of the muzzle at moment of discharge but not close enough to be an actual contact shot)[1]. Gunshot wounds from point-blank are identified by extensive powder burns as well as tissue damage from perforation by unburned grains of gunpowder.
Now...instead of there being no actual contact...there is actual contact. And bearing in mind she shot it in where our temples would be. One of the most vulnerable parts of our body. As for the shotgun, got nothing for that so touche.
But like us haters have been through many times, the stupid pistol hurting the Aliens are half of the reasons this film shouldn't be sent in the past. But that last comment, oh, the irony in that just made me laugh. I love it when you people attempt to be intelligent.