Seems like the idea is that "girl with gun" is a gal who's doesn't follow which way the wind blows, and doesn't play coy either, but instead is headstrong and decisive enough to set her sights on the fella she wants and is willing to follow through with pursuing him. To go on further, this can be intimidating for a fella - intimidating enough that he'd dodge her for someone less forward. But according to Tommy's account, it's her willingness to pursue him that's awakened his own forthrightness, and it has lead to great things for both of them down the line.
Seems like the idea is that "girl with gun" is a gal who's doesn't follow which way the wind blows, and doesn't play coy either, but instead is headstrong and decisive enough to set her sights on the fella she wants and is willing to follow through with pursuing him. To go on further, this can be intimidating for a fella - intimidating enough that he'd dodge her for someone less forward. But according to Tommy's account, it's her willingness to pursue him that's awakened his own forthrightness, and it has lead to great things for both of them down the line.