Back in the 60s Skeeter Skelton wrote articles dsescribing how to cobble up shot loads for revolvers. Being in serious cottonmouth water moccasin country, I followed his instructions and rolled my own for a lot of years (until the CCI shot caps were readily available).
The CCI caps work well, and firing one or two will NOT foul your shooter. I have them in 22 mag, 38/357, 44/44mag, 45 Colt, and 45 ACP. The 45 ACPs will cycle flawlessly through my Kimber and my ParaOrdnance 45s mixed in a magazine.
Shot caps do work, and they work well, but only out to around 15 or 20 FEET (not yards). IMO, they're all but useless on game or clays... but YMMV.
These days I prospect in serious rattlesnake country so, I still use them (though more often, I have a shotgun handy). Having said that, I've not needed to fire a shot round at a snake in close to 15 years IIRC.
Midway USA sells the Speer plastic capsule that you can fill with shot and thus easily roll your own. I have them in my cabinet but have never used them.