This is the oldest problem in the book, and is faced by pretty much every detectorist.
You will notice that nickels on the XLT come in anywhere from 18 to 22 on the VDI readings.
Bottle caps and pull tabs can range anywhere from 12 to 48 on the readout.
This means if you set the discrimination too high, say above nickels, you will be missing a lot of nickels and some valuable jewelry.
If you are just starting out, most people will recommend you dig up everything, so you get a feeling for which signals are valuable and which are not. Sounds like you've already learned that lesson.
Couple thoughts - and you can decide for yourself.
If you get a target at say 38 you know it's too high to be a nickel and too low to be a penny, dime or quarter. Try scanning from a different angle. In other words, if your coil is first swinging
North-South, try scanning it East-West instead. Does the reading change? If yes, it's most likely asymetrical, like a pull tab. The bad targets are usually jumping all over the place anyway in their VDI numbers. Is it a solid signal or broken, like "bibb-ib-dit-dit-dit?" If broken, that's another clue that it's junk. If the area is full of trash, most experienced operator will skip it.
That in my experience was the hardest lesson to learn - to just give up when you have several indications it's trash.
What I do is: If it's a slow day with few coins found, I dig up everything.
If it's a trashy area, and I've already dug up a dozen or so pull-tabs and bottle caps, then I start skipping the dig for bad readings. Once you are familiar with that oh-so-wonderful sound of the solid coin signal, and the meter reads 79 or 81, you are pretty danged sure you have a good coin, and it's easy to start skipping the trashy (VDI-30 to 40) signals.
Hope that helps
I run my reject at 5, I just dug a V nickel @4 inches and it was a chattery signal, I usually gig everything in the + vdi scale except 95 cause thats where the coal comes up, doing yards around here theres gonna be hot rocks.
