LS-Remember....as I have always understood it and someone can back me up on this...the coil size and build characteristics are responsible for the depth potential of the machine at that particular time, it is seeing EVERYTHING in the ground that it can see with that particular coil,YOU cannot change this. What YOU are changing is what it reports to you,via processing,discrimination,sensitivity settings,etc. It sees 100%,you may tell it to tell you about only 10% of it through settings. If you want to see things stupid deep,you need a stupid big coil,generally,in good ground. In very mineralized or iron contaminated ground a coil of a lesser size may be able to tell you BETTER or MORE ACCURATELY down to ITS depth potential because the machine isn't fighting to process the signals of all the iron flakes or minerals,due to the coil "seeing" less ground. For example,a 10" coil may have the depth potential in good ground to penetrate to 12" and see a quarter. In bad ground it may be only able to tell you about that quarter at 7",if you turn the sens up any more there is a point of diminishing returns. However,an 8" coil may be able to tell you about the quarter at 8" in the bad ground,because it doesn't have as MANY minerals and rust flakes to deal with. ALSO,a larger coil is generally more susceptible to EMI(power lines,transformers,etc.). This is why so many people have so many coils. Two coils of the same size from different companies will perform differently,to some extent,sometimes to a large extent. You have to see what works in your hunting spots,conditions within FEET can and do vary greatly,though it's common to set it and forget it for an entire day. And definitely don't forget the "move on" thing....this also has to do with diminishing returns. If a site ain't giving it up,move along. If you only have 3 sites to hunt,lower the expectations and hunt for pride. I have a farm that whoops my ass 9 out of 10 times,but I still hunt it. It's to improve my skills mostly,anyone can dig change at 4" in clean ground,I'm not that guy. I want to eek out every keeper out of the junk and terrible conditions,the skills will serve me well later. Part of doing this is seeing what coil works the best in the nails,which one is better than others in big iron,which one is better by the road in can slaw,etc. What will work for YOU in the end must be determined by YOU. Get a sniper,a medium coil and a large coil and use the hell out of all of them. Time will show you how they work and why they work well in specific situations. if you're looking for silver in bad ground,good luck with a huge coil. If it's good ground with few targets,you have a good chance.
HH
Kevin