To clarify, the "all-metal" is a term that usually means a static non-motion mode like on older detectors but with modern detectors it can also mean
using no disc in motion mode. One still has the benefits of the ID meter and tones to discipher between signals received.
So I was referring to motion mode without using any discrimination.
Detector technology is not at the point where we can ignore all pulltabs and be 100% sure we get all the nickels.
But for casual detecting, we can cut down on the number of pulltabs and still get some nickels.
Since pulltabs have been made with various alloys and sizes over the 40 or so years, they register down a little below
the nickel range and some will read almost as high as the zinc range.
Generally speaking, larger rectangular pulltabs and pulltabs with beaver tails read higher on some of the better ID detectors than nickels do.
Some of the newer pulltabs read very close to what nickels read so some of them can be a problem but some detectors with practice
one can ignore a lot of them if they decide to.
Depth and ground conditions also factor into how accurate a detector can give a right on reading of what's in the ground.
Now I am going to get into whether to dig all pulltabs or not, that is for each individual to decide how he wants to detect but if someone so
decides on playing the odds on digging less pulltabs then there are detectors that can accomplish this.
Using too much discrimination or discrimination either a little higher or lower than what nickels read, can cause a detector to give broken
or not give a signal at all on a nickel.
That is the reason many use low or no disc and go by the ID system, tone and meter reading of the detector to make a decision whether to dig or not.
Note I mentioned "casual detecting" because serious detecting takes on a totally different mindset.
Like if I am relic hunting, I don't use any disc(or in the case with the Explorer a low iron mask setting) and usually dig all signals that give me a clue there is a non-ferrous item present.
Now there is no way I am going to do that at a modern park that is full of aluminum trash of all sorts, I generally will select conductive ranges do dig.
In other words, in such situations, I don't dig foil or lower conductive pulltabs if I am mainly going for silver coins.
While it is true that anyone who digs every signal will get more finds, time is always an issue for all of us so we can pick and choose what to go for.
Those looking for gold like on beaches generally dig all pulltabs and foil to find jewelry and some who do this ignore the higher conductors, such as
quarters, dimes and pennies.
Detecting is an individual thing so everyone has their own way to go about it.
Hope this has somewhat answered your question, if you have the 70, feel free to PM me and I can give you more info about that particular detector.
You may also want to read some of Andy S. books on this subject because he goes into details about selective digging.
HH