"[W]e might, perhaps, be inclined to give consideration to this assignment if defendant had made a general objection below assailing the witness in his character as an expert or questioning the probative value of ballistics evidence. But the defendant did not do that. The testimony of the witness covers forty–six pages of the transcript. It is interspersed with numerous objections to particular questions on particular grounds, but we find no general objection except that the evidence bullet, concerning which the witness was testifying, had not been properly identified, and we have already ruled that objection was properly overruled. However, we will say that, while the question is a new one in this state, we are satisfied the rights of the defendant were not prejudiced by the admission of the ballistics testimony. It has been held competent in a number of other jurisdictions when given by a qualified expert."