Originally Posted by
Bleve
What happens to the CG airborne when all rounds are fired?
It seems that the aircraft retains the cartridge cases on board.
"the empty case is transported back to the drum "[1]
"M103 case 1,855 grains.
Total cartridge weight ranges between 3,865 and 3,965 grains depending on exact type."[2]
So at least 1855 / 3965 * 100 = 47% of the mass remains in the aircraft after firing.
Fuel use/state may also be a factor that is considered.
[1]
F-16 Armament - M61 A1 Vulcan
[2]
http://navybmr.com/study%20material/...14313A_ch7.pdf - page 5 table 7-1