The 1911 was designed to function in almost any environment. It was solely for the battlfield. In assuring it would always perform, Browning designed it to be loose, so as to prevent jamming from debris. It is also very easy to work on to allow field maintenance, has many modular parts to allow replacement of components rather than the whole, and was originally made from heavy steel. After WW2 GIs were bored, and knew how to shoot, but accuracy was limited from a loose pistol. Gunsmiths (read: machinists) discovered that tightening frame to slide fit made the pistol accurate, but less than reliable--not an issue with bullseye competition. When Jeff Cooper began demonstrating importance of pistol in civilian world, Frank Pachmayr, Austin Behlert, Armand Swenson, and othets found that through careful machining, extant parts could be smoothed to reduce resistance, slick up function, and therefore make the gun reliable. The loose, heavy guage, modular 1911 could be tightened, cut and ground, and have new parts manugactured and added to old frames, to begin to make the mastetpieces we have today.
Think about it like this: frames and slides have changed shape very little since 1911. How many machines at the height of their popularity today can say the same?
