A question - have you tested another bolt in your gun or had your bolt tested in another gun? I recently purchased a spare bolt (no idea if S&W or MK) and I took the new bolt out to the range. I bought the gun used and had never fired it before. The original bolt seemed to work fine. I swapped out the bolt and the gun would fire but every couple of rounds an empty would get stuck (with the tip of the empty crushed). I swapped the bolt back and the gun ran again. I compared the bolts and the difference seems to be with the extractor length. The bolt that did not work well has an extractor that is slightly shorter than the other. I will get some pictures. I also have several spare extractors that came with the spare bolt along with a set of old instructions about how to fine tune an extractor with a file / vice. I will scan these instructions and post them later this week (am out of town). I may be mistaken but I think that these may have come from Tim Lafrance out of SD, CA. There are receipts from Lafrance included with the parts lot that included the bolt, extractors, etc. At some point would you consider sending out your bolt for testing in another gun and trying another bolt in yours? It may be a quick and easy test to try to get things to work. I will post pics and scans of instructions later this week. Oh, a footnote - the MK that I got uses unmodified Swedish K mags. The mags lock right in and the gun runs fine with them. I've owned several MK and SW guns before and none of them used standard Swed K mags (actually were Suomi stick mags with the loop). I was surprised.
