Here's a book that can help if you're looking for some reference poses for females in combat positions.
There's a bit of everything in it, with models posing in different costumes, holding different guns from small pistols to huge shot guns. There are photos from the front, top and bottoms-up positions.
You can find this book on amazon.co.jp. If you buy from the link, I get a little commission that helps me get more books for review.
Here's amazon.co.jp shipping rates for your reference.