Hi Again Joe,
To run the ATX super quiet at Long Beach in wet sand, you will have to ground balance some and at Seal Beach a little. What I have found, the farther down the coast you go, the less ground balance you need to run totally quiet in wet sand.
And your right, the threshold is totally smooth, stable, and not a peep unless you scan over something metal or bump something hard. Rubbing or bumping the sand has no affect and makes no sound, but if you bump a rock or hard object, you will hear a little twang and feel the vibration up through the shaft to the hand control.
The sling that comes with it works pretty good for me as far a taking the weight off while scanning. Carrying the ATX to and from a location to use it, is like carrying a lead pipe
I've been looking into modifying my shaft also. I found a carbon fiber tube on eBay that is 40" long X 1-1/4" diameter that would work perfect. But the way the coil is designed and mounted, I don't want to have to cut my existing shaft at this time.
I don't have any concern with the stem nuts, mine always seem to turn just fine.
I'm getting better and better with junk targets. You can measure longer items as rods, wire and stakes as you scan like with any machine. Aluminum can tops or bottoms scream at you at any depth. You can hear nails, bobby pins, and small wire with the double tone sound or use the Iron Check to about 4". Some nails that are deeper will not make a double tone. If I scoop a faint sounding target on the first scoop, I run the iron check over the pile of sand I just scooped, and about 50% of the time it will grunt on a small iron something, so I just move on.
You can hear shallow foil with a high tinny pitch sound. Those deep Taco Bell hot sauce packs drive me nuts because they make a decent high/low sound.
When I see and hear a faint small target and don't retrieve it on the first scoop, I get excited, but most of the time it's a lead sinker way down there, and sometime it's a iron bolt or object down 16"
The low/high and the high/low sound helps with the type of metal on most items, but it can be fooled on deep items, but at least you hear something.
...Bill