So...I got the rubberized Pachmeyr grips (for a Model 39 which is what the Model 52 is based on), installed them and went to the range today. They did not turn me into a professional shooter and my shooting is still suffering from bad old eyes and shaky old hands, but the groups were at least not stringing as before. They were round.

It must be not that the gun moves in recoil while the bullet is still in the barrel, but that the action of pulling the trigger had my hand slipping on the polished hardwood completely smooth hardwood grips. With the rubber grips the stringing problem disappeared. Interestingly over the years many of my pistols include those rubber Pachmeyr grips used because of feel and look. I have no other pistol with such smooth grips as came on this used Model 52. I have never had a flinching or anticipation problem with any of my guns so I knew that was not it. But it is now solved. Thank you to those of you that commented.

LDBennett