Most modern combat jets don't hold too many cannon rounds. You fire in short bursts when you know you can gain a hit.
Most Russian jets don't carry too many shots on 'em. For example, most variants of the MiG-31 have a 6-barreled gatling cannon. The GSh-23-6M can shoot over 9,000 rounds per minute... the MiG-31 carries less than 300 rounds of ammuntion if my memory serves me well...
If you're ever researching military data, don't ever settle on Wikipedia as a singular source. I can't tell you how many times I've looked for data on even mundate systems like the Mk 80 bomb series and not found consitent data. Finding data on guns is hard, too. I was researching the M39 20mm a while back and had a really tough time getting the information I wanted... in which I had enough sources saying close to the same thing so that an accurate figure could be produced. If you had to have a singular source, get your hands on a copy of "Jane's Air Launched Weapons." That still probably won't be perfect even, and then there's the thing of actually getting a shot at reading it...
By the way... Nice work on those, people!