The problem with a pin pointer sounding off when pressure is applied to the shaft, is that shaft is a coil, and unless it's filled with epoxy then the windings will distort and even a little distorting due to pressure/flexing will cause falsing. That's why most coils are filled with epoxy, because coil winding alignment is critical to stability and performance. If you ever use a coil that isn't rated waterproof there is a good chance to instability due to temperature changes, bumps, or rough swinging, all of which can distort the windings for moments in time. Is that Minelab filled with epoxy in the shaft? It if is then it should be stable even with stress on the shaft for the most part, but I bet it would then weigh a good bit more than the Garrett, even if the Minelab is using micro ballon technology (something they mix with epoxy to make it lighter) that is the reason why epoxy filled coils these days are so much lighter than they used to be years ago.
A lot of solid (pancake) coils of yesterday were not filled with epoxy in order to save weight, while spiderweb coils almost always were even back then, but they were heavy compared to modern spiderweb coils due to the micro balloon thing. That's one reason why the old BBS 8 and 10" coils on the Sovereign/Excal were boat anchors, while the modern versions (Tornados) of these coils are so much lighter. A non-epoxy filled coil can not be rated waterproof, and while some use them in water they have a tendency to float, and if it gets one pin hole in the coil case it's probably lights out for the coil. Surprisingly, I'm told the new 13" Ultimate coils are only rated water resistant. These are super light coils for their size, so I suspect they aren't epoxy filled. Filling a coil with epoxy is the only way to lesson the risk of water finding it's way into the coil's windings and any electronic components it may have (some do).
An easy way to tell if a solid coil is epoxy filled is not only by weight, but try pinching the coil with your thumb on top. Does the plastic dent in? Then chances are it's not epoxy filled. I owned a certain white coil (solid with a hole in the middle, but no names) for a certain line of machines made by an aftermarket company. It was the only 12" coil I could get for these machines and so I wanted one to push my depths deeper. While I had heard some others say the coil worked great and got them more depth, on my particular model (same frequency/same coil compatibility) would go bonkers after about ten minutes of use. No amount of lowering sensitivity, turning the machine on or off, removing the battery, or anything would fix it.
Hmmmm...Must be EMI? So I move to a remote site down the road. Same deal. 10 minutes in and it goes bonkers again. This happened for about 3 days and drove me nuts trying to figure out. I even sent the coil back and got another new one thinking it was a bad coil. Ten minutes with this one and I pop one or two pretty deep mercs, deeper than I ever dug with this machine before! Success! Nope...A few minutes later and this coil went bonkers too! Drove down the road. Worked fine for 10 minutes, then same deal all over again.
So I sent that coil back and got a refund. Up until about 2 years ago when I started researching making my own coils, I never could figure out the mystery of what that coil was doing. Then it dawned on me after researching how to build my own coils. That stupid coil was white for a very good reason. It wasn't filled with epoxy to keep it's weight down, and so the coil would warm up in the sun after about 10 minutes and the windings would move ever so slightly out of alignment and the thing would go nuts! AHA! Coil winding alignment is even more critical on concentric coils than DD coils. For that reason, to this day, I am always suspicious of white coils. Why make a coil white? It seems kind of illogical when it's being moved around in the dirt. That coil was white for a very good reason...to try to keep it from heating up in the sun.
Now, I'm not knocking all white coils as being as delicate as that coil was. I've seen a few modern white coils (such as the Ultimate, although I hear they make it in black now too) that are white, and yet it seems to be getting some very good reviews. Even if a coil's windings are secured well without using epoxy and shouldn't move due to temperature changes, being white should help keep the coil in super tight alignment so it performs perhaps a hair better and thus allows slightly higher sensitivity settings perhaps, so by all means don't avoid a white modern coil even if it's not filled with epoxy, as technology has come a long way since I first bought that white coil years ago. I'm going to be the first in line for an Ultimate when I have the spare money to see how it compares to my 12x10 (which I love), but I hear they make the Ultimate in black now, and just for cosmetic reasons alone I would rather get my hands on a black one, if not for any superstitions I've developed over the years.
