The proper way to determine overall length of a 1911 platform .45 ACP cartridge is to remove the barrel from the pistol and use the barrel for a gauge.

When the overall length is correct, when you drop a loaded round into the chamber with the barrel held vertical (chamber up) the base of the cartridge should be flush with the barrel hood. A few thousandths shorter (like .005") is better than too long. If too long, the slide won't close. When using cast bullets, I want mine to be absolutely flush so that the cartridge headspaces on the bullet for consistent ignition.

When using a jacketed bullet, slightly long length (even just a few thousandths will keep the slide from closing completely). The softer lead bullets will allow the slide to close when nearly shut but the MUCH harder jacketed bullets will not. So, when using jacketed bullets you must have a few thousandths more clearance (a slightly shorter overall length).

Dale53