1. I already read Why do fighter jets still have guns/cannons?, but it doesn't expound why 100-200 rounds suffice or how "6 seconds is actually a lot of 'gun time' for modern air-to-air systems considering speeds, targeting systems and lethality of the projectiles involved."

I acknowledge that "It's not like WWII anymore where you'd slowly pull up behind a bomber and then have to spend several seconds pumping a bunch of crappy .50-cal lead in, hoping to poke enough holes in an oil cooler to make a difference."

Revolver cannons

"The Mauser BK27 is a 27mm calibre [revolver] cannon manufactured by Mauser (now part of Rheinmetall) of Germany. It was developed in the late 1960’s for the Multi Role Combat Aircraft programme that ultimately became the Panavia Tornado, it is used on a variety of aircraft including Typhoon, which carries 150 rounds."

"For that role the [SAAB JAS-39 Gripen] aircraft is armed with a 27 mm Mauser BK-27 revolver cannon with 120 rounds and with up to six short-range AIM-9 Sidewinder air-to-air missiles."

Rotary cannons

"The F-35A is armed with a 25 mm GAU-22/A rotary cannon mounted internally near the left wing root with 182 rounds carried". The Dassault Rafale fighter "is equipped with the GIAT 30-millimeter cannon with 125 rounds of ammunition."

MiG-35 "is also armed with the 30 mm Gryazev-Shipunov GSh-30-1 autocannon with 150 rounds.". "The Su-35's armament includes a GSh-30-1 30mm autocannon with 150 rounds".

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    $\begingroup$ Fighters don't attack ground targets. That is what attack and ground support aircraft are for. $\endgroup$ Sep 12 '20 at 10:54
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    $\begingroup$ To elaborate, even if they can (with limited ammo), attacking a ground target with cannon exposes the fighters to unacceptably high level of risk getting shot down. $\endgroup$
    – Jpe61
    Sep 12 '20 at 11:04
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    $\begingroup$ Many smaller air forces these days don't have dedicated ground attack aircraft any more, they use multirole fighters instead. $\endgroup$
    – Hobbes
    Sep 12 '20 at 13:06
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    $\begingroup$ About 15 years ago, the Air National Guard accidentally strafed a school in New Jersey. The pilot fired 27 rounds, of which 7-8 hit the school and did just shy of 1 million dollars' worth of damage. And those were practice rounds without the explosive charge, and the pilot wasn't even aiming at anything, he just accidentally pulled the trigger. So, it looks like 100-200 rounds is enough to demolish about 12 to 30 buildings. $\endgroup$ Sep 12 '20 at 17:50

They don't need more rounds.

  1. Modern fighters contain a targeting system that can calculate where the bullets will go, allowing the pilot to fire only when he's sure to hit the target. In some aircraft, the gun is slaved to the targeting system so it can be set to fire automatically when the target crosses the firing line.

In WW2, aiming was more primitive and usually involved firing a long salvo, using the tracer rounds to see where the bullets go and adjusting your aim to hit the target. This required far more rounds for a kill.

  1. The gun is a weapon of last resort, to be used when all primary weapons have been expended. It doesn't make sense to add a large gun magazine when that would reduce the primary payload.

  2. Gun strafing has been superseded by cluster bombs. Since the 2008 treaty forbade their use, small smart munitions have been used instead.

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    $\begingroup$ By mid WWII the British had introduced the Ferranti lead computing optical gunsight, which became the K-14 in the US (those sights you see in P-51 photos with the rectangular reflector and two collimator lenses) and you no longer needed tracer to help with lead angles. Watch old WWII gun camera footage and you'll notice a lot of them show no tracer being used. Those pilots had deleted tracer from their ammo loads having mastered the computing sight, and this gave a bonus tactical advantage because the enemy plane got no warning from tracer going past them. The K-14 was called "The Ace Maker". $\endgroup$
    – John K
    Sep 12 '20 at 12:23

More rounds means more weight and more space needed to store them. Guns in jet fighter are not there primary weapon system anymore but are there as backup to save you when leaving the war zone after your mission or give unexpected and unplanned support to ground troops on your way back and when you know that 1 good round is enough to put an airplane out of order, 200 in backup is quite a few tries.

On the other hand the A-10 has a gun as primary weapon and has 1150 rounds in typical support missions.


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