I will post this next with a suggestion that I just looked at an LCP2 and two M and P 40s, and a 9mm, 40 and 45 Shield and an EC9s. None are headspacing on the extractor with any cases I have.
A 1911 is even less likely to.
The chamber ledge near the start of the rifling for straight wall and even bottleneck is there for a reason. It is functioning most of the time as a head spacing surface is why. I will suggest that extractor headspacing may be more fiction than fact.
With bottlenecks the handloader may choose to size such that the case shoulder controls headspace. Factory ammo likely has the shoulder so far back the case mouth does that job.