When people talk about their 1911’s, it is normal to hear people say things like “the tolerances on my pistol are incredibly tight. It doesn’t make any noise when you shake it.” This is a description about the fitting of the pistol. The tolerances of the pistol was never actually described in that sentence.
If we were to talk about the tolerances of the pistol, we would have to talk about the consistency of the part dimensions from lot to lot. Tolerances literally means the allowable deviation from the originally specified dimensions for a manufactured part. Anyone who has worked with blueprints has most likely seen this before. For instance, when companies are producing arms for our military, they are expected to keep the tolerances very tight in order to guarantee interchangeability of parts.
When it comes to fitting, we know that tight fitting can give a pistol a feeling of having superior build quality and better strength. In some cases, tighter fitting can lead to longer service life and a better consistency in performance. The downside is that sometimes tight fitting can result in fouling from foreign particles like dirt and sand to cause more friction, risking more malfunctions and failures to cycle properly. Looser fitting can be viewed as a more reliable quality, allowing more room for fouling to build up and not cause friction. But on the other hand, loose fitting in pistols and rifles, aside from the AK-47/74, can be considered to be a sign of a sloppy quality of manufacturing.
No matter what your views are between tight fitting or loose fitting in your guns, you need to know that it being tight fitting is not the same as the tolerances being tight. A custom 1911 that is hand built with parts slowly filed down until they barely fit is not based in tolerances. Know the difference, and use the terms correctly.