The RCBS .45 ACP Shotshell dies are mentioned in an article Shot Loads for Big Bore Handguns in Handloaders Digest, 11th edition. The procedures outlined, credited to C. E. Harris of the NRA Technical Staff, use various .45 ACP, .41 Mag, and .38 dies, but said that the RCBS die set speeds up production.
Basic procedures:
Cut a .243, .308, or .358 rifle case to 1.250, and trim to 1.180.
Size and decap in a .45 ACP die, do not expand.
Neck size in a .41 die to establish a shoulder. The shoulder should be located so the base of the brass is even with the barrel tang. The shoulder sets the headspace, and too much will lead to misfires.
Prime (The table showed a CCI 300).
Powder charge with 6.0 grains of Unique.
Trim a .410 wad to 11/16 inches and insert.
Add 90 grains (approx) of shot.
Set a .38 gas check skirt down, and lightly crimp with the .38 die.
The text said 6.0 of WW 231 would also work, and that a paper overshot wad could be used in lieu of the gas check. You can make an over shot wad using a sharp-mouthed case. It indicated the .45 ACP shot shell was the most difficult of the cartridges in the article to make.