Thank you for your service as well Air Force.
If you are new in detecting and have watched the DVD or read the manual for the 505, I would recommend you dig everything to get a handle on the tones. Personally, I don't even use the depth display as for the most part, coins will be on the surface to about 3-4 inches deep. That is not saying they can not be deeper but most will be in that range.
I've been detecting since 1982 and believe me, there will always be something out there that will fool you, no matter old school had to learn by Sound or new school by Tones. Now a Pocket Dump of coins can be a blast to find but it can also give multi Tones so keep that in mind. And in the Pin Point mode, I can almost every time, tell if the target is a beer or pop can. I'm unsure of how best to describe it with the 505 but the All Metal Pin Point sound (not a Tone) will be more distinct than on other targets, almost having a slight buzz in it. My Garrett Freedom II pin point makes a much different sound, almost as if hollow, and I can be almost 100% sure when I have found a can. The instructions though for the 505 or my Garrett do not tell you that so it comes with much digging and reminding yourself with more digging. You can know the history or use of a place by people but you will never know what you are going to be in for until you put a coil to the ground. For example, try detecting for coins at an old shooting range. Yes, you can do it but with much patients.
I don't know that any of us have it so down as if to know everything about the back of our hands but years doing it will get you close. I have found with the Tone detectors, that I can hear at times a most subtle change with the tones while visually relating it to the ground and the movement of the coil over it and when suspect enough, I will dig it. Now if you suspect a sound in All Metal or the Tones in the Discriminate mode, dig it. Better safe than sorry. You would be amazed at times at what you almost passed up as junk. One rule of thumb we use with Gold nugget detectors (all metal detectors) is, the area of ground that sounds in relation to the coil movement over it will be less broad for valuables (Gold) than for iron or hot rocks. You can apply the same to the 505 in the All Metal mode. It is not a perfect indicator of what you have but it can in effect be used as a very basic form of discriminating.
You will find some guys will absolutely refuse to dig anything less than a certain discrimination setting and others will not dig Zinc pennies. Everyone to their own but the more they discriminate or refuse to dig, the greater the chance they will miss things for me to find. Last winter I cleaned out a river beach of coins that I know for a fact has been hit by metal detectors galore. The unit I used was a Whites Goldmaster V/SAT. There are no bells and whistles on that machine, no discrimination, and is All Metal. Ya, I found as well tent stakes, fish hooks, hair clips and pins, lead sinkers, pull tabs and cans for instance but I also got the coins others did not, which were mostly quarters, nickles, dimes, and a very few pennies.
Have a great weekend Dirt Fishing, Robert
