So I have a Gen 4 Glock 22 that I've been looking to possibly convert to 9mm as a possible ZOMBIE APOCALYPSEgun, so I can shoot two calibers out of it. (Luckily I bought some 17 mags before the ban came into effect). I am looking at a lone wolf conversion barrel and I am aware that it is recommended that I change out the recoil spring as well as the barrel. Now here is where I have a few questions. I know that I can get an aftermarket gen 4 Glock 17 recoil spring or, I can get a gen 1-3 style spring with an adapter to fit the gen 4 slide. I am curious as to what you guys (the ones with experience with the different recoil systems) think of this? Also, I have read in certain forums and seen some videos where people recommend swapping out the ejector and the extractor, I am curious if anyone familiar with the conversions changes these out or not? Is there a difference is reliability if I just keep my .40 extractor and ejector? or is it a big enough difference that I should change them? Thanks guys.