Des,
Are you falsing in both all metal and discrimination mode ? Where is your sensitivity set ? There is a beach here in NJ that is loaded with black sand and iron. On that beach, I run my BHID300 in all metal and on the preset sensitivity. I ground balance 2 times to make sure I am in the correct range. Also, I continue to check the GB every so often as conditions change pretty quick on this beach sometimes.
I have found that 90% of the time, I am using the unit in all metal. There are times when there is a small rise in the threshold, and no lights go off. These are deep targets....sometimes very small. They could be anything, but I dig them. Found a small gold plated toe ring at about 6 inches as one of these targets that did not make the lights go off but had a rise in the threshold.
I feel I am getting better depth and can even determine the targets better in all metal.
If you cannot ground balance the detector, try the GB setting right in the middle, all metal and sensitivity at preset ) possibly a little lower. Also, a very low audible threshold.
Just so you are aware...I am hunting salt water beaches.
JC