A WWII Training Area found

I was metal detecting in the woods because all my regular park spots are pounded very well and I need a change of location so I tried the woods. I heard that the military used to practice not too far by here and now its all woods. And I went deep in hopeing to find some old coins but I started getting a zinc hit on my Ace 350 pretty shallow maybe 4 inches. Now when I'm in the woods I useually dig shallow signals that I normally wouldn't dig in a park area. So I dug it up and it was a long old brass shell. It was pretty cool to find one cause I could tell it was old. And I found a shell similar to this before and was told its WWII era. So I moved several feet back and got a bunch more hits similar to the shell from before. And they were all long case machine gun bullets. Most dating from the 40s. Pretty cool! I also found an old rusty piece of metal that looked like it could have been part to a gun but I didn't bring it back cause it was too rusty. So I'll probably be heading back. I found most of these shells within inches to a foot away from each other. And near by was a tree that had lovers initals and a date of maybe 42 or 45 on it. So its an old area. I was only there for maybe two hours. I didn't search really well. I don't know what could I find in an area like this. Should I dig iron signals? What would you guys do? Here are pics of the shells. Some say L C 43, some say R A 44 ans some say U 43, and one says SL 43. The quarter is for sizing. Thanks for looking and HH!