Agseeker A nail hit north and south will give a deeper reading than a nail east and west this is because the detector is only seeing the narrow part of the nail , east west the detector is picking up the signal between the center of the coil and the outside of the coil witch gives your double hit . The coil is seeing the nail from the side coming and going . On a coin and nail in the same hole , let say the coin is laying in the center of the nail on top of it this makes the thin hit you have north and south wider than the thin hit with out the nail witch makes the signal closer to the east west hit thereby giving a more consistent reading both ways . Not quite as good as a coin hit but the depth #s will be closer together than a nail by itself this is because the nail has made the coin hit longer one way than the other but the longer the nail the more difference in the depth reading , the shorter the nail to coin size the better and closer the #s will be. Most nail coin hits will be only off a inch not two or three . But there are a lot of different size nails and the way they lay in the ground next to or on top of a coin .out there which will give different readings . As far as falsing the chirp or cut short coin sound you here is the false what you must remember is a coin that is accepted will sound round and have a longer coin sound than a a false so audio is your first and most reliable indicator . Most people think coins that are left in the ground from a pounded spot will be deep but there are far more coins that are in the 4 to 6 inch range that are mixed with some type of thrash. If you work a spot and most coins in that spot you have recovered are in the 4 to 6 inch range than those hits that are jumbled at 4 to 6 inch range should be carefully analyzed , try to circle these hits looking for a high tone using the tip of your coil once you locate the good tone pinpoint if it stays where you pinpoint dig . All my sites have been pounded and I still find coins that are quite shallow but are mast one way or the other . Depth has not much to do with age of coins you can find a Indian at 3 inch or 9 inches in the same place . It's more likely to find a deeper Indian than a shallow one simply because all the shallow coins are gone and where easy to find . But don't let that fool you there are plenty of shallow old coins that are there that are mast .