This Is essentially a process of grinding from the reinforcement material which was included to strengthen the buffer tube/extension space, and reprofiling the region to really make it resemble the original A1 space. This will include some welding or filling of some kind. Use the pictures underneath as an example: https://landenewnff.cosmicwiki.com/1096623/how_colt_combat_elite_commander_45_acp_can_save_you_time_stress_and_money