I had to set a lighter spring in my entire sized M16 A2 clone but it ran great. Attempted again While using the 11.5" Comando Colt higher. No dice. Ran 500 rounds of wolf by it nowadays. Didnt hurt the spring in the slightest degree.I tried a lighter H1 buffer and a very heavy eight.two ounce . The H1 exact detail as well as eight.2 would eject but