If it punched down when he tried to go under it, he would've died. Simple as that. Apollo's rifle is clearly listed in his profile AND in a thread for Ironfist Arms/Armor. There were better ways to down it, hell, a blaster bolt to the head would've been a better idea because it would have AT LEAST stunned it.
I know, however, Yavin 4 is home to the Sith right now. Number one, your padawan going in will be suicidal. Number two, there is martial law, and ships are grounded in Imperial space. Number three, going under the radar will be an impossible task, you'll need to change it.