hi gary I used gb at 90 but on other fields have used pump gb doesn't seem to make any difference in what gb I use have not tried xy, will do next time and yes its hot rocks not coke etc. large iron not huge pieces sound good with a bit of iron buzz but found a brass rifle casing that sounded like iron but with a little bit of high tone so I thought I would dig it anyway and was surprised to see a brass case ? I did not dig as much iron in 4.1 version with your ultimate program it was either iron buzz or good tone.thanks.