Need some FReeper help here. I now have my dad's Model 11 Remington shotgun. It's a 12 G, 2 3/4" shells, serial number 744763. Mod choke. Made 1940s or earlier. I'd like to clean and prep it quite thoroughly prior to its trip to a gunsmith for a safety/ops check. Anybody have a good source for how to dissemble/clean it? many thanks!