Using the M6 and 5.3 eclipse coil. When I get a reading that bounces from 18 to 22 I will try and scan the edge of the target,just brushing up to it,if its a pull tab the signal will break up,most times. If I get a signal thats 18 ,you can bet its a nickel, if its under five inches. This is on modern clad. I dont think Ive found a nickel any deeper than five inches so far.
Like rcasio44,I watch for bouncing numbers especially if it goes over 20. But,with the M6, I use the multi tone mode and a nickel (to me) has a unique sound and when you hit a zinc,copper,dime,quarter theres no doubt after you make multiple scans from different directions,its gonna be a coin under your coil. Nickels want give the same sound as dimes,pennys,quarters on the M6 so I dont know what it would be like on the MXT.
I have had this happen to me on the older pull tabs minus the beaver tail. Ive gotten a double beep.
I have to decide when I set out on a hunt if Im gonna cherry pick or dig most or all. Ive never found a nice ring or piece of jewelry but Ive read and been told,If you gonna find the jewelry you gotta dig the tabs.
Hope this helps from my limited experience.
HH
Gator