130GR .38 Special FMJ is the old M41 round. The Air Force issued this in their revolvers for a long time. It's pretty anemic, but great for target shooting. You will wear out before you wear out a S&W revolver shooting that stuff.
Keep in mind that your 66 and 642 will be sighted for 158GR ammo. So they may not shoot to point of aim with the 130GR stuff. With the 642 you're stuck, but with the 66 you can adjust the sights. I wouldn't worry too much about it though.