Pinpointing tone with the Ace250

Something I have noticed lately with my Ace250, when pinpointing, the tone either drops off slowly or very abruptly when moving off the center of the target.

When the tone drops off abruptly, begin by looking right on top of the surface or just under the grass instead of digging a plug.

I have picked dozens of coins at the lake like that this year, scratch the surface and pick up the clad, saves on the digging time.

Aluminum screw tops also seem to produce this effect.