If he wants another configuration, he can grab another upper assembly and slap on it. IMO there are many undesirable features on these older Colts. Pivot pin can be of a style that requires two flatblade screwdrivers to remove. Pivot pin retaining pin hole and weep hole are often not drilled, preventing conversion to standard parts. Fire control group pins can be nonstandard, preventing replacement with nonstardard parts such as improved triggers. Sear block prevents installation of many improved triggers and legal use with legal sears. End of the bolt carrier is often milled off, causing uneven wear on the buffer.
