What does your brass look like? Deep scarring from the extractor? Is it ejecting at all? Dirty carbon ring on the neck and shoulder area?
I still think you have a cyclic issue, bolt speed is so fast that it's not giving the bolt catch or next round time to move before it's already headed the other direction.
I built a 358 Winchester upper that did this very thing and a few others. Everyone kept telling me to put an adjustable gas block on it. I read everything on the issue aside from the adjustable gas block band-aid. Then I found an article detailing adjusting the buffer weight to cure the issue. I ordered several H2 and H3 buffers and a few of Slash's Heavy Buffer kits and the H3 solved it. The Slash's kit made it a whole different animal, cutting recoil and improving the quality of the ejected brass. I was getting the little ding from the deflector, with the Slash's kit, that went away as well. Slowing dwell time will improve chamber seal and stop that dirty carbon ring on the neck and shoulder as well.
If you are having extraction issues, remove the double spring and any rubber under there, they are band-aids for poor extractor quality. I use NB BCGs, but keep Tromix extractors and spring kits at the ready, the 375 and 458 Socom will educate you quickly on real extractor quality.
