Dave reacts by crying when his father violently shakes him and demands that he tell the truth. From the text, we can see that Dave is visibly distressed by the murmurs of condemnation from the crowd.
Dave actually doesn't stop crying until Jim Hawkins tells him that no one is going to hurt him. Dave then begins to confess that he had never actually meant to shoot Jenny (the mule). He had only wanted to see if the gun worked.
The next question is from Dave's father, Bob, who wants to know how Dave came to own a gun. For his part, Dave tells his father that he bought his gun from Joe at the downtown store. He also claims that he got the money for the gun purchase from his mother. In reality, the money actually belongs to Dave. His mother kept his pay because she didn't trust him to spend it wisely. For her part, Dave's mother wanted to use Dave's pay to purchase school supplies and clothes for him.
In the end, Dave manages to keep the gun in his possession. He runs away in the night and takes the next train out of town. Knowing that it will take the better part of two years to pay Jim Hawkins back for killing his mule, Dave decides to leave. In Dave's mind, leaving is the only way he can live freely, without interference from others.
In Richard Wright's "The Man Who Was Almost A Man", David does (not surprisingly) confess everything to his father when he begins to violently shake him and demand the truth. He tells him that he bought the gun from Mr. Joe. When his father demands to know where he got the money, he tells him that his mother gave it to him. David does, however, fail to explain that the money was his own and that his mother kept for it him because he was not responsible enough to keep it for himself. He does tell his father a lie, however, when he tells him that he threw the gun in the river. It is interesting to note that while he was willing to confess most things, he would not confess that he still had the gun.