Interesting statement from Bob Wright in that thread:
"Again, the main studs, that is, the trigger pivot pin and the hammer pivot pin, did indeed shear off, not once, but several times in my Model 29. And these were replaced with the newer pins. I'm not sure what process was used to get the sheared off stubs out, but they were replaced. And when I was at the factory, there was at least one other Model 29 having the endurance package installed. Maybe there were some things not done, but as to my gun, the shearing of pins stopped, the opening of the cylinder stopped, and the dual firing pin indentations on the case head stopped. The gun went on for around 15,000 rounds or more before I sold it."
I don't want to make impression that I am bashing S&W (I am looking now for S&W 629 DX -3 or -4), but those previous S&W M29/629 revolvers had a lot of issues. To be fair, almost all of them are on M29/629 models, when full power 44 Magnum ammo is extensively used. Softer shooting 45 ACP or 45 AR ammo just wouldn't do such stress on revolver, even older M25, before endurance package was introduced. I can understand when somebody wants older N-frame for collection, they were beautifully done. However, for shooting, I would go with later models, with endurance package (longer bolt notches), but with pin on hammer (my preference), because those revolvers do not have MIM parts.