I have never Dug one (I don't think) but from my book they look close .
Should be .50 cal, & the Book says Should have a 'Cone Cavity' The middle picture looks like it has a 'Small Cone ' the one on the right looks a little bigger.
I'm goon guess these bullets were fired or burned.
My opinion they look like Gallager bullets, just not 100% ....but close.