Oh, before I draw the obvious replay the the M1911 and M1903 for the pistol and rifle were years (as opposed to random sequence), those weren't done according to modern Army regulations. I'm not sure when those went into effect.
And I'm not sure about aircraft. Those are different, but I don't know why. But the creation of Army Aviation was very political and I believe the Air Force had and maybe still has a piece of the development and testing process. That may be why.