Sorry. First picture was wrong. Yes, lower in the web of the thumb. Right on the joint.
I have gotten to the point that most DA revolvers, above .38 Special, hurt.
I finally figured out what’s going on. I have dainty little hands. Exceptionally strong, just small.
N Frames and even K Frames, the horn of the gun is not centered in the web of my hand. If I Center it, I can’t reach the trigger very well. Any grip that adds more cushioning helps with the recoil but, I need to turn the gun further in my hand thus directing even more recoil into that thumb joint.
I discovered this by dragging out an old SP101. Though smaller and lighter than an N or K frame, I can center the gun in my hand. The recoil is still there, just not that sharp “damn, that feels like I hit my thumb with a hammer” pain.
Pondering sacrificing an old K frame and thinning and rounding the whole backstrap, from the horn to the bottom and, see if it works.