Supposedly the original 357 Magnum loads were less powerful than newer rounds, especially those with 125 gr bullets and lighter.
Nope.
At the time the Model 19 was introduced and took over the police market by storm, the standard factory load was a 158 grain lead SWC bullet using 2400 flake powder, at 40,000 PSI pressure.
On top of that, the bullets were too soft, and they leaded badly and increased pressure further.
That was followed by the first JHP loads from the Super-Vel company. They were the first 110 & 125 grain JHP loads to hit the police market in the 1970's.
They were loaded with ball powder, to what must have been +P pressure, as they were way hotter then other .357 factory loads from Winchester & Remington.
My personal feeling is that a lot of those loads got shot in dirty Model 19's with badly leaded forcing cones left over from the 158 lead bullet loads.
To further compound the problem, police range training sessions were shot with mass quanities of .38 Spec. target ammo, followed by a few cylinderfuls of Super-Vel to see what they were like.
With no cleaning the chambers or barrel first.
That sometimes lead to a Series of Unfortunate Events, and cracked forcing cones.
More recently, SAAMI has reduced the pressure standard on several calibers, including reducing the .357 Magnum to 35,000 CUP.
I have loaded for my Model 19 & 66 for many years using a 140 grain JHP over 14.5 grains 2400. This is a good mid-range magnum load that will not hurt any gun.
rc