My fairly new RCBS "Cowboy" dies would not crimp my 45 S&W cases, despite being labeled as suitable for both. My only 45 ACP dies are in my SDB Dillion so that isn't an answer.
Fortunately I have an older (25-30 years) set of 45 Colt dies on the back one loading bench. I got out the seating die and tried it with no success, so...I clamped it in my vice upside down and with a file dressed off about 1/8"-3/16" off the bottom of the die. It now ends right about where the outside threads start so it still screws into the press easily. I also took a round file and put a little more taper to the inside of the die mouth as I had filed most of its factory taper away.
The modified (shortened) seating and crimping die works perfectly with the 45 S&W cases so I marked the die box as "45 S&W" and now use it for that cartridge exclusively. The newer "Cowboy" die set is reserved for the 45 Colt.
YMMV,
Dave