In the many handguns I've fired at the range, I only found the PPKS to be uncomfortable after a box or two of ammo. I believe I found the reason, and by sharing it, perhaps it will help someone else with similar problems on other guns. It might apply to some of the guns mentioned in this thread.

The best way to illustrate the problem is to put your (right) hand in a position as if you're holding a pistol, with your finger on the trigger. Look down on it from above. Your index finger and thumb form a backwards "C".

On most guns, the backstrap of the grip rests in the approximate center of the web formed by your thumb and index finger. But, if your index finger is short, you compensate by rotating the "C" counterclockwise to rest the tip of your index finger properly on the trigger.

By this rotation of your hand, the backstrap now rests on a bone at the base of your thumb. Repeated pressure on this bone from the recoil of the gun makes it sore.

Padding might help, but it's a clash between the geometry of the grip, trigger and your finger.

I'm interested to hear if anyone else has a similar problem, and if they came to a similar conclusion.

Hope this helps.

Fred