I bought an early 4506 (hooked trigger guard) from an LEO that was in excellent shape.
On the whole, a very good gun in my opinion.
These were specific to my gun, but an area to look at:
1. Until the extractor was adjusted, it did not like Remington brass. It fed everything else perfectly, but not RP or UMC headstamps!
2. The trigger breaks later than I am accustomed to. I don't mean a long pull (it is) but the sear didn't trip until the trigger was ~1/4" from the frame. Training issue...
Overall, I am very happy. I'm still sending it to the PC for a trigger job, but that's because I want to, not because it has to go.