I wonder if it is the difference in our soils or if our machines are calibrated just a tad different. Interesting and thanks. I have only had foil and some smaller shot gun head stamps give me a solid 13. I think one or two beaver tails also.
I have not hunted a spot with the newer pull tabs. I am only hunting old campgrounds at the moment.
After a little more time of using the 600, I'm seeing that almost all nickels I have dug read as 12/13 (bouncing back and forth betweeen them) or sometimes 11/12. I have not dug a solid 13 nickel. All solid 13s I have dug have been modern pull tabs (the kind that are SUPPOSED to stay attached to the can - who pulls a pulltab off anyway?)