Can you ID this little artifact?

[Codyjp]

I found this while diving Catalina a while ago. the neck is gone so I can't determine the Caliber. I also can't make out any numbers on the bottom of the shell. It is big though. it must be .50 at least. I considered sanding it down to see if I can expose any type of markings, but I am not sure about doing this. Any ideas of what it is or where it came from?

 

[The Kraken]

Well, had you placed a ruler next to it in the pics it would have given some indication of the length and width.

If it's less than about 1.5" in diameter at the bottom of the case it's probably a .50 BMG.

Anything larger you're looking at a 20mm or larger.

the K

 

[RICHinNC]

Might just be me...but dont see the pics

 

[jlyle]

During WWII, Catalina Island was occupied by the military. You will find many spent shells from that period around the islands, fortunately, only fired in practice. If you want more, dive San Clemente Island.

 

[The Kraken]

Probably the spent casing from some aerial gunnery practice which, by the sheer preponderance of the weaponry used in both bombers and fighters, would more than likely cause it to be the .50 Cal. BMG.

the K

 

[livewire]

If you really want to clean it up a little water/vinegar mix will clean up some of the calcium deposits. Test it out first to make sure you don't wear too much off of the metal's finish, but maybe it's not necessary. I'm with Kraken and I think it's most likely the .50 Cal. Browning Machine Gun. Fits the time and place. Here's a pic I got from Wikipedia that might be helpful. The .50 Cal is the one on the left:

 

[Codyjp]

I am also thinking a .50. It really is big. I will have shot I think at cleaning it up.

I think if this thing hit you on the head after falling from a plane it would kill you for sure!