OK, here's the deal on that "Nulling" you are describing. When the Excal "nulls out" that means you lose your threshold but you aren't actually getting a "signal", or at least nothing repeatable. What it USUALLY means is that you've gone over something that is discriminated out. Now being a beach hunter, you aren't running any discrimination. Or at least you don't think you are. Because you have it on "1". But there's one thing that the Excal discriminates out automatically and that's iron. So it's entirely possible that you are running over iron. Rusty metal, fish hooks, bobbie pins, BOTTLECAPS(!!!)...lots of those things will cause the Excal to null out and lose the threshold.
That said, it's also possible, as you have astutely noted, that there may be a target of value there that is too deep to accurately register as a good target with a repeatable tone that would compel you to dig. Chances are that it's the former situation...ferrous metal...iron...that is nulling the machine. What you need to do is to use the threshold to determine when you have nearly missed a target...like when you passed close to it but not close enough...or when you have a target that's sufficiently deep enough to SEEM like a null but in fact when you slow down and attack the target from a few different angles, you end up coaxing a "diggable" signal out of it. That's the beauty of hunting with a Minelab (or certain other) machines that have a threshold as opposed to those that do not. For example, my Fisher CZ-70 is a great detector. It gets deep silver and it hunts very well at the beach too...great depth, good on gold. Problem is that it has no threshold and it WILL miss targets that the Excal finds. Due to the fact that if I miss the target by just a little bit, it doesn't hit on it. But if I miss it by the same amount with my Excal, I'm very likely to get a break in the null.
So you have to decide when to dig and when to move on. And when all is said and done, those who dig EVERYTHING dig a lot more trash but they also dig things up that other of us who are more selective tend to miss. Like small, deep diamond rings. Like chains. Like expensive stainless steel watches. Of course you will get a lot of those things too...just by virtue of having an Excal and running disc at 1...once you get proficient with it. And you will. But when you get very good with it you will even have a kind of a "6th sense" on those types of things you mention. To where there will be some little thing that will tell you "DIG THIS!" And you will also gain the subtle ear and experience to know when a decent sounding target is actually a Heineken cap with the crown-side down or a null sound is that same Heiny cap with the crown-side up. And when a "crackly" sound has enough "gold sound" mixed in with it to be a nice gold chain and not a rotten tin can bottom. Sounds crazy, but it's not...many here can attest. The way to get that good is to get out there and get the swing time in and practice, practice, practice. Just like anything else.
Hope that helps...
