I had a 6" blue Python many years ago. Put around 6,000 rounds through it before I traded it off. I traded for a Colt Single Action that had some sentimental value to me.
The first day I took my Python to sight in, I loaded my usual handloads into the thing and could not close the cylinder. The bullets protruded from the face of the cylinder! These were 173 gr. cast Keith bullets with a healthy dose of Hercules (then) #2400 powder, which I had been using in my Blackhawk with no problem. Later had the same problem with a Smith pre-Model 27. And the odd thing was, a Model 19 Smith digested these without a hitch. Didn't want a steady diet of these in a Model 19, though. So when the Model 586 Distinguished Combat Magnum came out, I got hold of first one, then another, a 4" and a 6". After about 10,000 rounds through each, I've come to the conclusing the Model 586 is the best Double Action .357 Magnum to come along yet.