The .45 ACP
which was the predecessor of the "super" version of the .45 auto cartridge was a relatively low pressure round. During the time of its creation the use of modern fast burning nitrocellulose
powders were not yet very common hence the relatively large case capacity of the .45 ACP to accomodate a larger amount of slower burning powder.
Because of these two reasons, the case of the .45 ACP was not manufactured to be very sturdy and the chamber of 1911 pistols were not designed to fully support the case. The case itself was strong enough to hold the pressure.
In 1988 Dean Grennells designed a new cartridge using shortened versions of the .451 Detonics magnum and called it the .45 Super, it was to be a higher pressure, higher velocity cartridge that had the same external dimensions of the .45 ACP and could be fired in .45 ACP guns with just a barrel change or in some guns, even just a change of the recoil spring.
This allowed for a 230 gr bullet to be shot at 1,100 fps, a full 300 fps faster than the traditional loadings of the .45 auto.