Regarding GBing the Garrett. I am talking about real world conditions in soil vs. air tests. In highly mineralized soil, the Garrett, even after being ground balanced initially, would false if you put in a deep hole in mineralized soil or if you merely buried the tip in the soil pile pulled out of the hole. So you would have to GB it again to keep it from falsing. The problem was, every time you re-ground balanced it, you were also reducing sensitivity to the point that the Garrett would become somewhat useless in deep holes in highly mineralized ground such that you could not pinpoint the target unless you were right on top of it which might not be possible if, for example, the target was buried deep within in the sidewall. Even with the high sensitivity, I have not yet seen the MI6 false when properly ground balanced, which is a good thing. The true test will be real world highly mineralized conditions which I have not encountered since getting the pinpointer. Hopefully, I will have a chance to test that out soon.
