Nice. I like the details of the gun and the background but there are a lot of points i like for you to improve.

First, her arms seem to be joined together. Her right arm is suppose to be in a position where it wont stress her wrist and her left arm has to support the rifle by holding the stock to further absorb the recoil since it is an anti-material rifle (idk if it is true). Add safety glasses to make look cool and to protect her eyes from debris

Second, the distance between the scope and the shooting eye is too far. Adjust the head not too near or it will cause your character a black eye. Make your scope a little bit thinner and add knobs to make it realistic and the bipods thicker. It looks like it is gonna break the moment she pulls the trigger.

And lastly, her notebook. It must be on her non-shooting side otherwise you are trying to make her shoot with her left hand.

Overall, it is great. She has a good overwatch over her friends and good posture. Dont take this too seriously. Keep up the good work!