AceShowbiz - Singer/actress Miley Cyrus almost quit her role in new action movie "So Undercover" when she was reduced to tears after learning how to fire a gun. The teen superstar, who shot to fame on Disney TV hit "Hannah Montana", plays a private investigator who goes undercover at a college sorority in the Tom Vaughan-directed movie - but the gritty nature of the part was almost too much for Cyrus to handle.

The 17 year old managed to overcome her fear of firearms and has since hired a personal trainer to help her master the moves for her demanding action sequences. She tells MTV.com, "I've been doing fighting, like learning how to box... mostly like street fighting, so knowing how to, like, if someone comes up from behind you, being able to defend yourself. I have a trainer and I have bruises everywhere from, like, kicking the bags..."

"And I've learned how to use guns, which was really scary. I cried the first time, I was like, 'I'm not doing this... can't do this movie,' (but) then you get used to it, you get used to the feeling. You get used to, like, dropping, like he'll point it (gun) at you and you've got to drop down real quick and grab your weapon and come back up."

Cyrus is now starting to enjoy the rigorous training sessions and she hopes to retain the moves for her own personal safety when she's out and about: "It's been really insane, so it's a more fun workout than running on a treadmill. I want to learn how to do most of my own stuff. Just for normal life, I think every woman should know a little self-defense."