USSR and NIGHTLORD40K, you are right and also wrong. The L-frames were developed because of the switch by police departments to .357 magnum and .38 Special +P ammo (both ammo types). Also, at this time, many departments were starting to use carry ammo for PRACTICE and qualification. This played havoc with the K-frames.
The police departments and competitors both complained that S&W K-frame revolvers were wearing out, suffering from frame stretch and going out of time.
The modern designed RUGER Security Six and slightly larger framed COLT revolvers were not affected to the same degree that the K-frame suffered.
Also, the 110 grain .357 magnum is among the lowest pressure .357 ammo. Today’s 110 grain .357 reaches 1300 to 1350 fps, while the hotter 125 grain ammo runs 1400 to 1500 fps. It was the 125 grain that was so hard on guns.
My agency started issuing the old FBI gun, a K-frame, the S&W model 13 with a 3 inch barrel and round butt when I went through the academy. We were issued 110 grain jhp ammo. Later, some of the 125 grain jhp meant for another agency got into our supply chain and we were told in no uncertain terms to NOT USE IT. We had at least one model 13 crack the forcing cone. I had a privately purchased L-frame, a S&W 681 and was given as many boxes of the 125 grain ammo to practice and qualify with as I wanted. You knew the 125 grain was the hotter load from the very first shot. I had a foot long fireball coming out of the muzzle, so bright is clearly showed to the firearms instructors in the tower on a mid-August day in South Florida.
Way back in the 1970’s, I bought some 110 grain ammo and it was definitely hotter than the stuff sold now. It advertised over 1400 fps. However, the 110 grain ammo developed a reputation for having pressure variations outside normal limits and it was downloaded till it became stable.
