There are, and have been, many murders committed by women using all sorts of means. Poison is very popular (especially antifreeze), hand guns have been used, Lizzy Borden used an ax.
In a case that appeared on television, a woman claimed she shot her husband by accident, in her sleep, by reaching under his pillow and shooting him in the head. It was accepted with a jaundice eye for awhile until detectives discovered that, that was the manner of death of her first husband also.
There was another where a female prosecutor/lawyer flew back East to shoot her estranged husband from the bushes, and then flew back home.
Such murders are frequently on popular crime documentaries. If you are unaware of them, you must not be watching them. Don't get out much?
There are many instances of women killing someone, sometimes with a gun, sometimes with something else. So, what exactly is your point?