Don, I like the 40 gr. rounds, here's my theory. I would think that the bolt weight,recoil spring are ballanced for a given pressure -(bullet weight) in a blow back design. This may not be correct, but it is my belief. Yes I have heard of the VQ exactedge extractor, no I don't use one, mine is the factory extractor. Basically, on this particular blow-back action, the extractor is used primarily for extraction of un-fired rounds. Mine will fire and function flawlessly without the extractor in it. Yours will also, once the stovepiping problem is gone.Yes I have heard that Ruger is using double extractors. I have not seen any yet, I also was told that this was Rugers orignal response to the early stovepiping problems. I have also heard that Ruger has suspended production on the 10-22 mag for some reason. I don't know if this is true, but my gunsmith hasn't been able to get one from any of his suppliers for several months. My bolt stop pin is factory and has around 10000-12000 rounds. It shows no sign of breakage, or bending.
Like I have said,clean the chamber every 50 or so rounds, just a couple of turns with a brush, nothing elaborate. Tighten the tension on your mags, this alone will help a great deal with reliablity, at least it always has on the 10-22's that I have owned. If these suggestions and a couple of hundred rounds don't clear the issue and you should decide to sell the rifle, PLEASE give me first chance. If there is anything that I can do to help, just let me know.
Ron