Hmmm?
"Another gun under development for a small combat aerial vehicle is multi-barreled and can fire 270 rounds onto a target in just .001 seconds without stress on the air frame or any drop in air speed."
270 rounds in one/thousandth of a second, with no recoil. No "equal and opposite" reaction.
A thousandth of a second is about time enough to fire one of anything from A barrel, or two of anything from two barrels. Not time enough to fire two anythings from one barrel.
Must be something like a few "recoiless rifles", shooting small rockets filled with darts.
Arf