Had a similar occurance today:
I was hunting today with iron vol on 3 trying to find a place where a structure used to stand. Discovered a spot about 20x20 ft with lots of iron and nails. Deus settings: 92 sens, 12khz, TX2, disc 8.1, reactivity 3 silencer 0, 3 tone, manual GB.
I get this signal somewhat of a high tone and very repetitive but seemed choppy on the edges. Looking at the control head while sweeping I noticed a sliver of the right side of horseshoe would show only on some sweeps. Screen showed 01 VDI on every single sweep. So I'm thinking iron, but the tone just sounded a bit too good. Pinpoint didn't reflect big iron but a target smaller but larger than say a coin, So I dug and it was a handle of some sorts made out of a green looking metal and was buried around 6 inches deep. After digging I swept with coil and the object read 54 VDI. I even scanned the hole with pinpointer and didn't notice any iron and went back into pinppoint and swept hole and didn't hear any signal.
The TID#s can and will fool you. Tone, tone Tone