Source: Internet Movie Firearms Database
The standard sidearm for patrol officers of the Los Angeles Police Department in the series is the 6-inch barreled Smith & Wesson Model 14 K-38 revolver. LAPD Officers Pete Malloy (Martin Milner) and Jim Reed (Kent McCord), as well as several other police officers, are seen unholstering and firing their revolvers several times throughout the series. Many suspects are also seen using this gun. At the time, the S&W Model 14 was one of the standard revolvers used by LAPD officers. This model was used for the first three seasons (1968-1970). In 1970 L.A.P.D. transitioned to the 4" S&W Model 15. The show also changed so as to be technically accurate. Something that the production was proud of. For those interested in trivia many of the heavy barreled 6" Model 14's were cut down to four inch barrels by L.A.P.D. armorers. Occasionally one of these converted Model 14's can be found for sale on the used market. They are popular with police revolver collectors.
Interesting ... I’m more into that era’s radios, the Motorola MOTRAC (which was introduced in 1959 and ran as a product line up to 1970 or so) of which I have several that work (in the ham bands obviously!) and the Motorola HT200 “Walkie Talkie” (of which I had one in the mid 1970’s on 146.880 MHz) ...