1911 Extractors

The function of the extractor is to extract the case from the chamber, then provide a pivot point for the ejector to toss the case out of the ejection port.
There are external extractors and internal ones, too.
Here's how to tell the difference by a glance at the gun...
With a gun design incorporating an external extractor, such as my Kimber Ultra Carry II, you'll see the extractor immediately behind the ejection port;


With an internal extractor, the appearance of the slide is smooth from the ejection port all the way back, such as the Rock Island Armory:


The damage to brass is sometimes done by extractors. To ensure they do their job efficiently, you have to take care to not misuse them. It's possible to over stress them, causing them to lose tension and possibly breaking the hook in the process. One way that happens is when people manually drop a round in the chamber and then let the slide slam full battery (shut) on that round. This forces the extractor to pop over the case rim instead of the way it was designed to function. The intention is for the case rim to slide up under the extractor's hook, which would not force the extractor to bend awkwardly backward.
Always let the firearm perform the intended function...stripping off the round from the magazine and feeding it into the chamber. Forcing the extractor to *pop* over the case rim is hard on the mechanism...and your 1911 will thank you not to do it.
Shoot safely!