I have used two Fishers, an F2, (pretty much a way less expensive brother to the F4 lacking only all metal and the ability to GB in all metal...ONLY), and then an F70...In testing targets show up real close to each other, maybe only a number of two apart.
I assume this discrepancy is because the F2 is like 5.6 kHz and the F70 is 13kHz...yours is a cousin in the FTP family so you are correct, yours should act and behave in a very similar manner.
On the 3 ringer bullets I have found they ranged from low in the zinc area, 50's or so, on up into one I found that acted just like a normal zinc cent at about a 61.
I was shocked when that one came up instead of a rotten zincoln.
Mine were never deep where I found them so if you are going after targets deeper than 5" the numbers could change or other things like if they are smashed, whole, carved could also affect them but every one was a solid signal I had to dig.
As far as buttons I have only found a few, a gold gilted New York Militia cuff button 2" deep in nice black soil that came in as a solid 51-52 and a cherished and rare Dragoon cuff button found with the F70 that was a super solid 45-46.
Again shape, size how it's laying in the ground, depth and soil conditions can affect all signals on any target.
Basically, if I were a relic hunter in a site where this kind of stuff can be found I would be digging all repeatable solid signals no matter where they show up for sure, maybe some of the iffier signals too but I have gotten too lazy over the years to dig a whole lot of those types nowadays.
I could miss stuff by not digging every blasted signal out there at sites like this but my sanity is still a bit more important to me than my finds.
