Model 1911 pistol production ended at Springfield Armory early in 1917, as Colt had increased production to the point that the small amount of pistols produced at Springfield was no longer needed. Model 1911 production at Springfield was not a separate part of the armory, and the area was needed for Model 1903 Rifle production. Only 2,412 Model 1911 pistols were produced at Springfield in 1917 while Colt produced almost 78,000.
The last 1911 pistol shipped from Colt in May of 1918 was in the 322,000 serial number range, right where the rougher, less polished pistols started. More than likely the time in the blueing ovens was also hurried up.