I get a kick out of seeing if some of the assertions found in forums like this will stand up to a practical test. In this instance, it was "You can cut the .45ACP case back to .750, drop it in the chamber, and there is no way the firing pin will be long enough to touch it." So I cut a primed case to .730" and put it in the chamber ahead of the extractor - just to see what would actually happen when I dropped the hammer.
As you can see, the primer fired nicely and also backed itself out almost completely. The point is that the 1911 does not depend on the extractor to hold a short case. That long firing pin carries enough momentum to ignite a primer even when it's absurdly far from the breech face. Don't believe me; try it yourself and let us know what happens. Only takes a junk case, a primer, and a couple minutes of your time.