Elwood I am no expert at all but this is what I found.
Using Notch set on wide knocks out everything between a Nickle and a true copper penny. You often lose Zinc Pennies.
Using notch on narrow knocks out everything between Nickle and Zinc Pennies.
I usually tune my disc knob to just below Nickles. I then set my Notch to hit good on a nickle. I use mine on Narrow because I want to find all the money including Zinc Pennies. It is frustrating to me and leaves doubt when I see a Zinc Penny laying on top and my Machine doe not pick it up.
Setting up like this knocks out most of the pull tabs.
If you get tired of Pull Tabs like I do sometimes, just set the Notch to the middle being Off and move your Disc knob to just below a zinc penny. This knocks out all Nickles, Jewlrey, and Pull tabs. Every signal you get will then be a Coin.
All things are not guaranteed, occasionally you will still get a misshaped pull tab sneak in just like on Notch, but most of them are eliminated. Remember rings and Pull Tabs are essentially the same. Hope this helps. This is a scale showing where the notch hits.
Wide Notch Null
Beep Notch Notch Beep Beep
Nickle Pull Tab Zinc Penny Copper Penny Dime
Narrow Notch Null
Beep Notch Beep
Nickle Pull Tab Zinc Penny
Hope this helped you!!!