While working in the desert, where rattlesnakes were a common concern, I used to assemble snake loads for .357 and .45 caliber guns for myself and others.
Mostly I just used metal gas check discs over powder and over shot. They worked and I tested them quite a bit. You'd get a spiral pattern and the "effective range was not more than a yard or two before the pattern spread so far as not to be effective. Usually the gas check(s) proved more fatal to the snake than the shot load
Better results as far as keeping the pattern together were obtained with CCI shot capsules, but they were somewhat expensive, for my available funding those days, for putting up a bunch.
I would think that if you use one of these capsules with #7 1/3 or #6 shot you would get a better more effective pattern, especially at ranges beyond just in front of your feet.
https://www.midwayusa.com/product/1010937313?pid=682652
They would be of the right diameter for your revolver and with 20-25 grains of 3F would certainly do the job and not be injurious to your pistol. You may have to cut them down to fit, reducing your payload,, but not much, if at all, I suspect. I also suspect you would have to remove the cylinder from the gun to load them though.
In defensive range though, (just out of reach), I believe a just a chamber with 20-25 grains of 3F with a wad and then topped by some #6 shot poured it leaving enough room for an "overshot" wad would likely be sufficient.. The idea of mixing the shot with lube as mentioned above also seems like a good one.
Alternately to the wads you could you the aforementioned gas checks as they are available in .452 and .454 diameters and being of soft aluminum or copper gilding metal I don't think they would harm you pistol, and they would leave more space for shot than wads. Just speculation on my part here as I have never tried this in a C&B revolver.