If you are asking me. The answer thus far is no. One junk ring that passed, one war nickel and other nickels. This system used in 1 small park city population small. Yet park contains numerous junk targets which is good. I got to look at them with hf2 and note behavior. Have also used on one small freshwater beach, 2 small church yards, one burned down hotel yard, did some lookin g in some some house yards.
Behavior in my area seems consistent. On the junk targets. System used to locate and place odds on digging nickels too, some which read lower and some higher on average. ID behavior changing freq yielded info making these targets suspicious. Not all were nickels either.
Expect to not dig any shallow and middepth older buried zincoln Pennie’s. Which can read in gold ring range. Expect to dig little less items resding in gold ring range. Expect to dig few square tabs or pull rings for actual nickels (exception stand out war nickel) could bahave like square or pull ring. Good system to due to place odds on gold ring existence digging fewer holes and covering more turf.