Just got my Siberian from TNA a couple days ago. Came with the updated firing pin. Tore the whole thing apart, and I'm actually impressed. I was worried that BCL was still doing NEA things and ####ing everything up. But the machining and finish looks good (Not just good for BCL, but actually good. This coming from a perfectionist machinist).
The gas system was aligned correctly, the set screws lined up with the dimples on the barrel, and all of the threads had loctite on them. Fit between the upper and lower seems pretty good (As good or better than most ARs). I'm bringing it to the range today to put a few rounds through it, so we'll see how that goes.
The only part that didn't look stellar was the bolt, but as long as it runs I guess. Aaaand it seems like the extractor spring is a little weak; I was able to move it fairly easily by hand. Wonder if that's gonna be a problem. Also the lack of any sort of buffer behind the bolt carrier seems... Odd. I guess it will have slowed down most of the way by then, but still? Might look into one, if it doesn't reduce the bolt travel too much and cause issues.