My Cu pennies USUALLY come in tighter than that; typically 23-26. Older V Nickels, Buffalo and Jefferson nickels are solid 12-13, Clad dimes 25-27, Silver dimes 26-28, Clad quarters 30-31, Silver half 34-35. I've been skunked on silver quarters, silver nickels and silver dollars so far.
I have turned up some older wheaties that dropped into the low 20's. Last week I found a 1910-S in the dust on the surface that was 20. That isn't typical though. My zincolns are typically 19-21. A badly corroded example can be lower than that by a couple digits; 17-18.
Currently, I am running v1.75 on my EQ800, usually in Park 1 or 2. I've bounced back and forth a couple times between v1.5 and v1.75 just to see if I can discern a difference. I mostly use the 11" coil, occasionally the 6".
Rich -