Being you have the GT and chance are you run in disc mode I would set the toggle switch that says pinpoint on it to pinpoint as this switch is only working when you go to all metal as this is the best mode to pinpoint in for me. Now i use 2 different ways to pinpoint a target, actually 3 if you count the one for surface targets where you leave it in disc. First way is moving the coil back and forth over the signal and narrow it down after you switch the toggle to all metal so the pinpoint option is on. Now with it just going over the target back and forth you can bring the coil back to you while still swinging the coil back and forth until the signal drops off as you know it is not under the hot band of the coil and you went pass the target. Now being I know it was in that small with I was swinging back and forth over I only have the push the coil forward a little bit, so I go forward and back with the coil and try to find that one little spot where the threshold drops off as this is where the target is. On each coil you will learn where the hot spot is and find the stock 10 inch coil seems to be back about a inch and a half from the tip of the coil. The SEF 12X15 on my E-Trac is back about half way between the tip of the coil and where the rod connects and feel for the GT it maybe about the same. This method of pinpointing is used on targets not very deep and most I can use my Sun Ray S-1 Probe to locate in all metal pinpoint, some are very weak signals with the S-1. Most are right where the GT says it is and can use my screwdriver probe and hit them first time. Now the second way which I use most of the time because they are deeper signals is getting the signal in disc and switch to all metal again as the pinpoint option is on if you left the other toggle in pinpoint. Now I will just go side to side and center the target the best I can, then push the coil down on that spot and turn 90 degrees and then go side to side again and center the target so where you get the best signal and it will be right in the very center of the coil is done right. If the coin is on edge or at a angle it can throw the signal off a bit and this is where the S-1 probe comes in and I am spoiled and cant detect without one anymore as no targets get misses anymore for me, plus so fast to retrieve a coin. This second method gets me dead on on the deeper targets that have a smaller signal.
I feel once you get used to doing this you will find it will pinpoint great, sure does for me.
Rick