Ammo ID

[ColinD]

Hi guys, I live on the Australian goldfields and metal detect, the by-products are often very interesting and give an excellent snapshot of the area's history. I find these rounds a fair bit, reading Steve T's excellent beginner guide (thanks! ) am I right in thinking this American round is from an aircraft? There were Americans training here during WW2, but I just wondered why these things would be in the middle of a forest. Shotgun shell base in last pic for size reference.
C

[sargetom]

I believe they were produced by Rock Island Arsenal in Illinois in 1942

[relicz]

RA Remington Arms - Bridgeport, Connecticut

[ColinD]

Yeah the article said Remington Arms.
I have some others FA 42, SL 42 and LC 42.
LC = Lake City, SL = St. Louis.
Are they fired from a plane?
Thanks for the help so far
C

[Adrian Stevenson]

Looks like a .50 cal, so could be from an aircraft.