Bounty Hunter Tracker IV wich coil to use?

Hello everyone have been using a radio shack discovery 2000 for some time.And only seem to hit coins .So i bought myself the Tracker  still havnt got my Tracker IV yet its on its way. But im wondering perhaps you guys can tell me .I ordered the 4"inch coil and i guess it can detect some small nuggets rings etc. But dont know whethere i should use the stock 8"inch coil in general or the 4"inch instead  ? Any ideas 

I have never used a Tracker IV, but have experience with a host of other machines with variuos coils. I do most my hunting right now with a Pioneer 202. I have used the 4" coil in areas I have hunted with the 8" to find coins that the 8" coil missed due to heavy trash, and the phenomena known as masking. This occurs when a trash object such as a nail is close to a coin, and your discriminator rejects the nail, and knocks out the coin also. The small coil has a better chance of seperating the trash from the goodies for retrieval. I hunt around older sites with the smaller coils, and where I need to cover alot of ground fast, or need more depth I go with a bigger coil. Both can be used on the same site, and both are capable of finding things the other can't.

Thanks Slingshot ill try your methods good hunting to you 

I have used the 10in mag coil on the pioneer 101 (tracker lV)  works real well goes deep found coins at 8in easy

bobby