i thought Navy F4 never got the internal gun and only the USAF got the gun?
You are correct. The first internal Vulcan cannon armed F4 Phantoms were F4Es of
the USAF. There were 39 Vulcan cannon air to air kills from 1966 to 1972 all were made by
USAF F-105s and USAF F-4s. Of the 10 cannon kills made by USAF F-4 Phantoms 6 were made by externally mounted
SUU-16 or SUU-23 externally mounted cannons. The other four kills achieved by cannon armed F4s were internally
mounted Vulcans in F4-E Phantoms. There were no USN F4 Phantom air to air kills achieved by cannon
all were by missiles. The USN F8 Crusaders are another story and achieved quite a few air to air kills with their cannons.
The Migs in SEA avoided the USN Phantoms in favor of attacking the USAF until they also added guns.
Don't know where you came by this information but it's wrong. Even if it was true. How would the Mig pilot know it was a USAF or
USN Phantom? If they avoided F4s it was because they were ordered to intercept the bomb carrying F-105s and A4s.