I still own a small collection of 3rd gen guns including some low production Performance Center pieces. I also have some VERY accurate pistols from other manufacturers including Colt, HK, Sig et.al.
The most accurate of them, in my hands, is my PC Shorty 45 MKII. At 15 yards it will put 7 rounds of Winchester RA45T into a sub 2 inch ragged hole. Freehand.
According to my shooting partner, who was the Captain of the Sheriffs pistol team, an instructor and a better shot than I, the most accurate gun I own, in his hands, is a 4506-1"dash 3". He gets a 1 to sub 2 inch group with that gun at 25 yards, freehand, using RA45T. I can get sub 3 inch groups at 25 yards with it.....if I don't drink the whole mug of coffee on the way to the local range.
IMO the inherent accuracy of this 4506-1 is due to the incredibly tight fit of the barrel to the side as well as the buttery smooth DA trigger and short crisp SA trigger. Back in the day s&w knew how to build a good looking accurate gun with a great trigger.
All that said, I have never come across a 3rd gen gun that I would call horribly inaccurate. My 910 pistol had a poorly bored original barrel that produced 4 to 5 inch groups at 15 yards with all manner of 9mm ammo. My smith replaced the barrel and the groups settled down th 2.5 to 3 inches at 15 yards using 147 grain 9mm. It remains my least accurate 3rd gen pistol....but still better than any 9mm the current company calling itself s&w produces today. Hope this helps. Regards 18DAI