True enought, the case was longer so the ammo could not be used in a standard barrel. However, conversion units were offered for non-Detonics 1911s so the round could be used. Cases can be made by cutting down .30-06/7.62X51 brass to a length of .942". Or you can trim .45 Win Mag cases to the same length.
The .45 Super comes pretty close to that but I dont recall if Triton offered the lighter bullets. They will physically chamber and shoot in regular .45 Autos - but the pressure is well over SAAMI specs for .45 ACP.
I have 50, .451 Detonics cases, and at least on the exterior, they appear to have much stronger case head construction than .45 Super or Winmag, which both look just like ACP at the head. The .451 case heads look like .30-06, with an extractor groove about half as wide as ACP, with lots more material in the web area.