gpz7000 on big targets

hello everybody, and first excuse me for my bad english but I am french. I plan to buy a gpz7000 with 19' coil (mono/DD coil) not to find gold (unfortunatly in france there are not nugget ) but to specific tresure hunting. before to buy the gpz7000 I would like to ask you something : for me it won't be to try to detect litle targets but big targets. so my question is : do you have an idea of the maximum rough detection depth of gpz7000 with 19' coil for a metalic target of 4 inches diameter in normal soil (in france ground is not as mineralised as australian ground) ? it's just to have an rough idea, I know well that maximum depth mean nothing, but at your idea is it close to 30 inches, 40 inches, 50 inches, 60 inches ?
thank you for your answers.

You would probably be better of with a GPX 4800.

They were made for the kind of hunting you intend doing.

Agreed,
No need to spend 10 grand to do what you want to do.
How deep do you want to be able to detect a 4 x 4 inch bit of metal?

Good advice coming from all members here Albert. The GPZ 7000 is first & foremost designed for gold nugget hunting, in areas of high mineralization. You'll find little advantage on depth over metallic targets 4" X 4" inches wide & above, using a 7000/19 inch coil, as compared to a GPX series or GPX 4800 detector, using an 18 or 20 inch round mono coil, over low/very low mineralized ground. In benign or quite ground conditions, some top of the line VLF detectors, give PI units a run for their money.

Cheers Kon.