Or the lock work.
Early model troopers had the same or maybe nearly the same lock work as the official police and pythons. They were extremely smooth and light but had a reputation of getting out of time after a lot of shooting.
Maybe around 1970 Colt changed to a more modern, more durable action but it never equaled the older action as far as smooth trigger pull.
I had a trooper mark III in .22LR and it was a good gun but with an action that could not even come close to my old official police .38. It was not as accurate as that old official police either.
The newer Trooper MkIII and MkV have a different lock work than the Python. The Troopers made before them were the same action as a Python, as was the “Official Police” (Barney Fife gun). It had fixed sights.
The Colt “D” frame (Police Positive, Detective Special, and Diamondback) had the Python lockwork scaled down on a smaller frame. The “New Service” was made before the Python, and it was a scaled up version of the old Colt positive lock.