I had to set a lighter spring in my whole sized M16 A2 clone but it ran wonderful. Tried out yet again With all the 11.five" Comando Colt upper. No dice. Ran 500 rounds of wolf via it right now. Didnt hurt the spring whatsoever. Which means the firing pin https://olivebookmarks.com/story20250852/the-ultimate-guide-to-forced-reset-trigger