Take a sharpie and black the extractor front half. Hand cycle a cartridge in, FA the bolt into place (if necessary), then hand cycle it out and see where the extractor contacts anything. That "hump" takes the place of the bolt lug that would be there if there wasn't an extractor. It should engage the barrel extension like the other lugs do. It definitely looks like it has been either polished by hand or by use. The gradual hook nose should slide over the rims a lot easier. That having been said. Looking at the image, it appears that either extractor would work. The one on the right needs some cycling to polish the surfaces. Other than that I like the more precise machining job on the right extractor, along with a deeper rim groove. An old trick from way back when, for using a 7.62x39 extractor was to relieve a little of the bottom of it back behind the rim groove to keep the "hump" from catching on the barrel extension and either bending or more often, breaking. The extractor on the right has that executed very nicely. Not as much relief as the one on the left but not necessary since the "hump" isn't as tall. Very good interpretation IMHO.
Hoot