Mike Wood just wrote a very interesting book called "The Newhall Shooting: A Tactical Analysis" about the famous gun battle in which 4 California Highway Patrol officers were killed in 1970.

He has a very interesting appendix in the book called: "A History of CHP firearms, equipment and firearms training". It was in about 1976 that the S&W 67 and 68 revolvers became standard issue. The duty load was the Winchester 110 grn +P+ jacketed hollow point (the "Treasury Load").

CHP officers could carry .357 magnum revolvers if they purchased the guns themselves, but had to carry the issue .38+P+ issue loads.

Most cops aren't shooters. Most of them seldom or never shoot in practice. For somebody who only shoots the minimum required during in-service training, a round that has less recoil will probably work better, because they can get back on target more rapidly.

I became a cop in 1981. The vast majority of cops still carried revolvers then. For those officers who carried .357 magnum revolvers, was common practice to use .38 ammo for training and carry .357 mag ammo for service use. Some agencies said that all officers had to shoot .38s regardless of what caliber revolver they had. Several agencies around here allowed officers to carry .357 mag rounds loaded in the cylinder but required all reloads to be .38s, presumably to allow officers to exchange ammo in the middle of a protracted gunfight . . .

I briefly carried a .357 mag revolver on duty, loaded with .357 magnum rounds. Some of my practice was done with .357 rounds and anytime I shot the gun in an IPSC match I used .357 rounds because they made major power factor. (The few times I shot in PPC matches with that gun I shot .38s I think)

I had never heard of the Smith & Wesson model 68 until I recently read Mike Wood's book on the Newhall incident.