I have not seen the Midway gunsmithing video in which Larry Potterfield demonstrates polishing the trigger and hammer. The key word is polishing and also using a fine India stone. The case hardening has sufficient depth that polishing should not remove it. The point to remember is that you are only polishing the surfaces, removing some of the high spots of the tool marks. When finished it is alright to still see someevidence of toolmarks in the low spots. I use Wolff Power Rib reduced pull mainsprings, but like to keep the factory power rebound spring and not going for a reduced power spring here. This is just a personal preference because I like a very positive feeling to the trigger reset. Get the Jerry Michilak VHS if you are serious about improving your M/18's trigger pull. Jerry walks you through the entire process, giving you great advice your trigger will feel great if you follow his instructions.