I was wondering if the Auto Rim brass would work. I notice the AR case has a fairly thick rim. Thought it might bind the cylinder.
There is a case out there known as the Cowboy 45 Special. It is an ACP length, with the 45 Colt rim dimensions.
I don't know of a source, just saw a few internet pages about it.
http://www.americanrifleman.org/wp-content/uploads/2013/12/45cowboyspecial_web.jpg
