How have courts dealt with evidence of personal use of a firearm in a murder trial?

In People v. Smith (2003) 30 Cal.4th 581 the defendant was convicted of murder and was found to have personally used a firearm during the commission of the murder. Police found a derringer and ammunition in the defendant's house. The derringer was not the murder weapon and the ammunition found in the house did not fit the murder weapon or the derringer. The defendant claimed the trial court erred in admitting this evidence at his trial. He argued that the evidence only tended to show that he was the sort of person who carried deadly weapons. (Id. at p. 613.)