Didn't even want to get into headspacing, but since you brought it up-
The .45 ACP does headspace on the case mouth on a standard case, in the Ruger Blackhawks. That's the Ruger problem.
.45 ACP standard cases USED to headspace on the case mouth in older Smiths, without clips, but haven't reliably for the past 6 or 7 years. Aside from the other issues I mentioned, clips are required in current Smiths for reliable ignition, and that's the Smith problem.
It's just a bad idea all the way round in revolvers, as CCI says.
In an autopistol, the extractor does help with consistent positioning of the cartridge for reliable ignition.
Even in autos, the .45 ACP shotshells from CCI do not always function. Some pistols will cycle them, others are single-shots & won't.
Have to test 'em in your own pistol before counting on them.
Denis