This sounds like a very dumb question, but has anyone (Manufacturer, gunsmith, wacko?) tried making an AR in .45 Long Colt?
Considering how popular lever action carbines are in that caliber it stands to reason that someone's going to put it in an AR platform.
Rimmed cartridges don't sound like a fun time for a magazine, let alone chambering a rimmed cartridge that should be headspacing on the rim instead of the case mouth in an AR.
Either way, such pursuits do seem rather noble, at least it would make for one heck of an engineering challenge.