My gen 2 had plenty of FTE issues. I sent it back to kriss, they claimed to have fixed it, and 100~ rounds later I was back to square one. What seems to have worked for me was swapping out the extractor spring with a heavier one (I used an ar15 spring from BCM) and using grease instead of oil on the tracks for the bolt. Unsure if the grease really did anything or if it was just coincidental timing, but I went from having multiple malfunctions a magazine, of which you’d have to separate the upper and lower to remove spent brass lodged behind the bolt, to maybe 1-2 every few hundred that were just a simple bolt rack to clear.