cartridge

I was metal detecting today close to Bull Run. Can anybody tell me what time frame these cartridges are from? The diameter across the headstamp is 12mm or 0.5 inches. I also added a 3rd pic showing the headstamp just in case that helps.

So, Iv'e dug many bullet casings while metal detecting most of them are post 1950's and I know that they are just worth the scrap value. But Iv'e also dug many bullet casings from early 1900's to 1950's and I wonder if they have some monitary value. Iv'e dug many readable dates casings from...

Please help me to identify! please identify cartridge and bullet big!