Wife gotta new Garrett Ace 150

[66Fairlane]

Went out in the yard to try out the wife's new birthday gift. The lead piece we thought was a musket until I realized it was hollow. Anyone have any ideas? It was round at some point. Looks like it was fired and struck something on the side but it being hollow confuses me. You can also see the center fire shot shells. One is a UMC Sureshot 12 ga, the second is a Wetsern Expert 12, and the last is a UMC New Club 12 ga. I think all three are from per-1940s. Found the normal trash as well. Any ideas on the round hollow lead piece would be appreciated.

 

[Diggin-N-Dumps]

Very Cool, ive been trying to get my wife out with my 250..it last about 5 mins..lol