I'm onto my 3rd bolt in my one. First one had been ground on the rear of the bolt lugs to head space, instead of adjusting the receiver or barrel flange. When we replaced the barrel with a new one, had to throw away bolt #1. It was replaced with bolt #2, which had not been ground on the rear of the bolt lugs. Come to find out that it had the face of the bolt (that engages the cartridge) ground away to head space sometime in its past. That clever deed altered the cartridge / extractor relationship. So now the rounds get ejected and stay inside the receiver, instead of going out the port. So just got through getting a replacement bolt at Sarco, which is the only source that was not a complete utter rip off (getting very difficult to find bolts now). Only catch is that my original bolt has a spring loaded firing pin, and the replacement is for a floating firing pin, so the tail end has to get a recess machined in it. I dropped it off at my smith a few days ago and he seems backlogged, so I may have to cancel and do the machining myself at work.
So far: Barrel parkerized inside at CIA, worn out stock knuckle - needed a new stock, original bolt modified and hence out of spec for new barrel, replacement bolt machined on the front and discovered to be out of spec, 2nd replacement OK, but needs to be machined to accept spring loaded firing pin. When I put in the new bolt, the head space will probably be off, so either re-cut chamber with a pull through reamer, or ship back to Jeff to fix it (hate wasting money on shipping).
From what I have seen so far, there have been several different "tricks" used by the assemblers in putting these together that turn what would have been good parts into scrap. The right way is first to be sure the receiver front face to bolt lug recesses is to spec. Then adjust the barrel flange if needed to get the head space right. This way, any replacement bolt that is to spec will be good. BUT, the A_holes in some cases grind the back of the bolt, which (provided your barrel is good and you don't replace it) at least will function if set up right. The next trick is to machine the recess in the bolt deeper if there is too little head space (clearly a lazy mans way since it is so easy to remove the bolt and so much harder to remove the barrel or re-cut the chamber in situ). But if this is more than just a few thou, the extractor will no longer have proper control of the empty shell and the rifle will never work again until you replace the bolt AND fix the original problem which is the too shallow chamber.
Sucks in some cases, but I have not given up yet...