I took it to the indoor range 1 hour ago and the new 18" bbl with rifle gas system and pinned gas block with muzzle break installed by me. It is a great "single shot" AR. It will extract and eject the spent casing but it will not strip and load a new round from the magazine. I have tried the factory Springfield Armory Saint Heavy Tungsten buffer which is marked "H", and I have tried a new Del-ton carbine length buffer which is unmarked. I do not know the weight of either of these buffer as my powder scale only measures grains. So I need the bright minds of all you AR experts solve this problem.