I Was questioning a similar detail. Low amp TIG welding may be the answer to just welding the roll marks. What's the perpose of copper? Could it be an real Class III transferable decrease or even a facsimile, or an illegal machine gun decrease? Cost will range quite a bit! https://martinnixpb.wikiannouncing.com/5677473/not_known_facts_about_colt_combat_unit_rail_gun_45