I recommend shooting rimless over regular 38 Super. The reasons for this are 1) rimless feed much smoother than a rimmed case and 2) you can get more rounds in the hi-cap mags.

All new Witness 38 super pistols are set up for regular 38 super rim. This means a rimless case has a little more play than we want to see for reliablility reasons. With a loose extractor you could have extraction problems so let's fix it.

1. Take the slide stop out and slide the upper off the frame.
2. Pull out the guide rod, recoil spring and the guide bushing.
3. Pull out the barrel from the slide.
4. Get a small pin punch and a hammer.
5. With the pin punch, tap on the extractor pin from the bottom side of the slide until the pin is coming out on the top. You don't have to take it all the way out, just enough to free the extractor to be removed.
6. Don't lose the extractor spring.
7. Okay, now we have the extractor. Get a small file and file straight down on the extractor "knob" until it measures 0.045", see illustration. This will allow the extractor to put more pressure on the case.
8. Put the extractor back into the slide, take an empty case and check to see if there's proper tension on the case.
9. Reassemble and testfire.

With this setup you may be able to shoot rimmed cases as well, but if you go lower than 0.045" you'll put too much tension on the extractor and the new case won't feed into battery at all.