Could've sworn I made this update which might have answered post number 52.
I looked at my technique and changed it a little bit. Instead of squeezing the slide with my thumb and forefinger and using that finger on the sights, I'm now doing a crab claw type grip with the 4 fingers and my palm. Doing that in a punching motion, and if I pay attention to my technique, I can easily rack the slide now from even uncocked position on an empty magazine. I'm not sure why, but the empty magazine makes the slide and slide release harder.
Anyways, I can do it every time now and send the snap caps flinging about the room. Some of them have landed a good 10 feet away. Any time I can't do it, I look down and find my technique has slipped and as soon as I do it I'm good to go.
It definitely was a workout for me to learn this thing and other guns wouldn't have required me to be so perfect but I've got it now. It is very satisfying hearing the loud rack and watching the snap cap eject.
Thanks for all the help. I put in about 6 hours of practice between the past 3 days and I think that's what did it.