"Error was assigned to [***11] the admission of evidence of a ballistic expert, who testified to the effect that the bullet taken from the head of the deceased was shot from appellant's pistol. That such evidence is admissible is now fairly well settled by the weight of authority. This question was fully discussed in a recent case by this court in State v. Shawley, 334 Mo. 352, 67 S. W. (2d) 74. The evidence was held to be competent."