Just found this info.....cool.

Specifications of the original military loading of the .45 ACP

Dimensions Minimum Maximum
Overall Length 1.256" 1.266"
Bullet Length .657" .667"
Bullet Diameter .451" .451"
Case Head .4718" .4734
Case Mouth .4672" .4732" (.4730" standard)
Case Length .892" .898"