DH is a paintballer, he loves his Tipman as far as guns go, but I wanted to suggest something you may not have thought of.
Once she gets a gun, she may want to play paintball with someone else. Unless she has ever been shot with one and knows what to expect, she may not know how much it can hurt. I'll never forget the first time my DH went paintballing with his buddies and came home. He took his clothes off and was covered with some nasty bruises

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If she wants to play, please make sure to look into getting her some gear. Jeans and a long sleeve top, doesn't cut it.
I got my DH a vest with a chest guard, a padded jersey, padded pants, and padded gloves. He's a "tough guy", and didn't think he needed all this until he wore them, and seen the difference! He loves coming out of a battle feeling fine, while his buddies that want to "tough it out" are in misery for the next few days, lol!

I got DH Valken brand gear, it is good quality, and if you do your research, you can get it fairly inexpensively

. I got DH a design that had been discontinued and was on clearance at the time and saved about 1/2.