Cody the problem is that your test does not accurately reflect conditions in the field e.g. the undisturbed ground matrix, moisture, ground salts, target and iron halos are missing. Further, positionally your test reflects only a tiny fraction of the possible depths and target orientation you may encounter in the field.
That said it would be wise to point out that like your test bench results there ARE target orientations in the field that DO hide the coin from us. We know this is true because how many of us have detected a spot up, down, and sideways with the stock coil only to then recover additional targets using an 8 inch coil. And of those recovered with the stock coil how many were difficult, single direction signals that vanished in the iron when swept from any other angle. Or we detect a spot clean and after two winter frost heaves that move things around in the ground several more coins suddently appear.
I had one particular target, a silver quarter and silver dime in the same hole about 8 inches deep. Now normally that would be a slam dunk target yet I could only detect this target with the front few inches of my coil. If I moved any further it vanished in the iron. If I swepth from any other angle it vanished. After I recovered the target I found a rusty nail at 9 oclock, 12 oclock, and 3 oclock. They were all a few inches outside of my 6 inch plug projecting their iron signals out over this target along the length of the nail. Forget a coin next to a nail, coins many inches from a nail can be rendered undetectable by the nails ability to cast an iron signal out along its length quite a long distance. I would say the Explorer has more difficulty with this orientation than when the nail is closer.
But back to your test, I don't question the result you are getting in this test yet I have found coins next to iron, fused to iron, holed with big crusty iron wire through the coin and a lot smaller coins than a quarter. I have a tiny silver knob about the size of a 3 cent piece with its big rusty iron screw still molded into the thing. There go those field results poking holes in our test bench data again.
Next and most importantly, none of us has a definitive understanding of what Minelab is doing when it processes the receive signal. Obviously they are looking at multiple samples, applying some logic and providing us with a result via audio and target ID. But without a definitive understanding of how the program code and/or electronics is arriving at this decision we are thinking in the dark. Our best data for understanding this machine will be observations made in the field.
May I add that target orientation is extremely important on deeper targets which again weakens test bench data. As you know the magnetic field lines do not flow vertically straight into the ground, they are curved. And so deeper targets that are often tipped slightly on edge intersect the field lines of different sized coils at depth at odd different angles. We see results of this often using the 15 WOT coil which has a habit of hitting stronger on deep targets than on shallow ones to the point that it will reach under a shallow surface target and get a strong lock on a deep silver on edge coin underneath.
Lastly, I have recovered quite a few coins by digging silent signals in IM -16. Hey wait a minute, that doesn't make sense. How can you get dead silence in all metal? You should either get a threshold or a target tone but not dead silence right?
Well if you come across a nail at 9 oclock and 3 oclock say 15 inches apart and inbetween these two nails you get a silent signal e.g. no threshold, no iron tones, dead silence, my advice is dig. It seems that when two nails are pointing towards each other even when this far apart they can cast an iron shield out over the coin. But its weak. The Explorer appears to get confused and can't make up its mind what sound to play and so it sits there dead silent wondering what to do. That tells me that A there is a target between them and B its not a nail.
Charles
