Dixie,
I've loaded these shot caps for a number of years now. I used to own a piece of land that was just broke out with rattlers.
Use the Speer plastic caps if you can get them. I believe my load is 6.5 grns. of Unique in the .44 Special. Use the smallest shot you can get as these caps just don't hold very much of it, and the patterns are pretty open due to the effect of the rifling. Frankly, #12 would work better.
I have taken a few bunnies at 15 ft. or so, and a couple of snakes at point blank range, but don't expect the shot to be effective beyond about 15 ft. A pop can at that range will take about a dozen pellets.
I seat the filled caps with finger pressure only as far down as the case will allow, then put a mild roll crimp on them.
Hope that this has helped you, and good luck with it! George
P.S., Beware of squib loads that leave the shot cup in the bore. I've experienced that when I fired these in my .44 mag. with a longer barrel. The next shot WILL get your attention!