You know its true, size matters. And not all coils are created equally. If you plan on being successful at finding gold nuggets with a metal detector you need to know which coil does what. Do you you want deep ground penetration or just to keep it shallow?
So what size of coil does what? To keep it simple, bigger equals deeper, smaller shallow. To give you an example lets say I was hunting a large, deep flat area that had the potential for large nuggets at depth. In his scenario I would use my 18 inch round mono coil on my Minelab GP Extreme. The 18 is a great deep coil and round penetrates deeper than elliptical, had to throw that in there, but a large elliptical coil would be fine also. But I certainly would not use my Gold Bug 2 VLF with a 6.5 inch coil or anything less than a 14 inch.
While I could use the 18 inch coil to hunt shallow bedrock and cover a lot of ground fast it would not be as sensitive as an 8 inch coil on the Extreme. The 8 inch would also allow me to better pin point my targets. Here again reversing the scenario above I could really use my Fisher Gold Bug 2 on shallow bedrock, that’s even better than the Extreme with the 8 inch in most areas.
So whats the perfect size? Well that depends on you and where you hunt. Personally I like my 14 round mono coil the best on my Extreme it can punch quite deep to get bigger nuggets and work shallow areas well enough to find very sub gram nuggets. Also, don’t forget bigger means heavier so keep that in mind. Smaller coils work brushy, tight areas better. Now I could really expound on this topic with all kinds of information and semantics but my goal is a quick overview.
As always, good luck and happy hunting!