I am on the same track as you (old fart with a bad back) but further down the road. I have settled on the Buffalo Bore 20D load, 125 grain JHP at standard pressure. With the powder that Buffalo uses this load generates 900 FPS at standard pressure.

I tried a number of loads in the 642, several were rather punishing and I was starting to develop a flinch. This load has solved that problem. You will not be able to shoot this lightweight effectively if you are flinching. I would rather hit my target with a controllable load than miss him with a load I can brag about.

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"Sacramento" Bruce Conklin