I have a friend that is a retired Fresno Sheriff's deputy.. I n the 90's and after he was the rangemaster for the department. They issued 4506's in the 90's in;early 2000's they switched to the 4566. The one I have serial# FS03XX was issued to a patrol deputy on 06/26/07. According to the information I have they issued approx 800 guns all with the FSO serial. Serial FSO 001 was issued to the Sheriff. Mine is in the high 300 range. Mine was purchased by the patrol deputy on 04/12/14 and he sold it some time later. Fresno Sheriff has approx 950 sworn. The 4506's were marked on the right side of the frame 'FRESNO SHERIFF' I have a couple of them. He was able to research mine and found that they were issued to court deputies , both showed little wear. Fresno now issues MP 45. I lived in Fresno County for about 4 years and still know a couple of deputies working there.