Luger actually brought out 2 units in 45 Caliber for evaluation by the US Army Pre WWI of course conducted in the Spring of 1907 there were 2 Luger's made in that caliber for the evaluation only 1 survives Serial # 2 the testing was extensive & quite brutal.
Source from my library ~ The Luger Pistol By Fred A Datig Pages 93 - 111.