If you disc out pull tabs, you'll also disc out some gold items and other interesting items. It will depend on where you're going to detect. At the beach, only disc out iron. If you're after relics of all metals, you'll have to dig it all. Modern urban park, copper cent and up is all I do. Old parks, schools, and homes with lots of junk, I only dig sex sounds (screamers and groaners ) I keep nickel sounds and everything zinc cent and up. Disc out the rest. If an old site doesn't have too much junk, or it's coughing up some great finds, and I'm not looking for iron relics, I pretty much do it like the beach.....dig everything non-ferrous.