US Test Trials White-Merrill .45 Caliber Pistol
15m
One of the domestic US made pistols entered in the US military pistol trials of 1907 was this White-Merrill design. It is particularly interesting because White and Merrill submitted a manual along with the gun, which describes some of their intentions and thought processes in developing the pistol.
White and Merrill recognized that they were competing against the revolvers then in service with the US military, and specifically tried to give their semiauto pistol all the capabilities of a revolver - things like being openable with one hand, easily able to check the number of cartridges loaded, and having sights fixed to the barrel. This resulted in some unique features, like the firing-hand charging lever, which allowed the gun to carried completely safely with an empty chamber, but still easily put into action with just one hand.
Unfortunately, while it had a bunch of innovation and clever elements, the design was not competitive. In the 110-round endurance test, it suffered 40 malfunctions of various types. That, of course, resulted in it being dropped from competition. White and Merrill would go on to design a better (presumably) pistol in 1911, but it was never actually sent to the military for testing.