I solved my gremlin problem, at least for the time being, by bending the sear spring to put more pressure on the sear. Yes, it makes the trigger pull a little heavier, but I haven't had any failures of the striker to stay cocked when firing ever since. Now, I have two bolt carriers, so in the long run I might end up tabbing one of them, just in case. However, if I remember correctly, I have also read here on CGN of welded tabs coming off when firing. So I guess that is not a 100% solution, either. All the same, I'll have one of my carriers tabbed, if and when I find someone who can do the work locally or somebody who could do it cheap enough and I could ship to.