Who said anything about Kel-Tecs? The poster. But only after an earlier response (it's content since changed) mentioned the FLAT K-T extractor that didn't use a spring. The original comment was about how it was made, and not, if I remember correctly -- it's not there anymore -- that it snapped OVER the rim.
Someone also mentioned the H&K P7, Luger and the Makarov, etc. I've shot a P7, but never really examined it closely, so didn't notice extractor function. I had an East German Mak and several Lugers, but didn't realize that those extractors snapped OVER the rim, rather than having the round fed from beneath/behind. I'm surprised but have no way to argue the contrary, as I don't have any of those guns, now, and that function is seldom mentioned in the articles available.
Interesting things you learn on these forums.