In Vietnam war, the US pilots resorted to engage Migs through WVR and from distant due to their strategy but there were still gun kills. But since then, there have been plenty of Gun Kills across the globe.
If you are looking at the US engagements across the globe and trying to determine "gun kills", you are looking at the wrong picture. Our strategy isn't to engage the enemy at close distance one by one. We establish air dominance and practically put in a no fly zone no matter how many fighters the adversary has. So when the other party has little to no chance of flying their sir assets to challenge the US military....how would they ever get to gun kills?
The F-22 is built on a similar concept, yet with a gun as an emergency option in case there is a Dog Fight. But its primary role is to disrupt and destroy enemy formations in bulk, before any US air assets can be exposed to the enemy. If a squadron on intercept is destroyed 60-75% by two -22's, way before the -15's or -18's get closer to the "left over" interceptors....what do you think the interceptors will be doing? More than likely, they'll be low on fuel, with moral destroyed, trying to run away from the invisible ghost that just destroyed 15 out of 20 jets! But if there was no -22 or a BVR doctrine, the regular jets would probably still get into a dog fight, specially if both parties were located in a close proximity.
