A 30mm round. The GAU-8 Avenger, the nose cannon of the A10 Warthog, shoots these rounds

if you're brave enough

thats not bravery, that's stupidity

a real woman would use the gun itself
it rotates you know

Its for killing tanks actually...
Back in the the late 60s/early 70s, America wanted something to kill tanks
So they made the Gau-8.
But they had an issue; the gun was fucking huge and it was hard to move.
What did they do?
The built the plane around the gun.
Thus the A-10 is born.

Yes I know the A-10 is my second favorite plane behind the Sr-71.

my fave is probs the F-4U