This Is essentially a process of grinding off the reinforcement material which was added to bolster the buffer tube/extension place, and reprofiling the area to make it resemble the original A1 space. This might include some welding or filling of some form. Use the photographs down below as an example: https://raymondeelli.shopping-wiki.com/8772008/the_basic_principles_of_colt_combat_elite_commander_45_acp