Denny, I think you're right, but a few details are off a tad:

Then Vietnam came along... And the Mig-15 was a quick, deadly, street
fighter ...

MiG-15 flew in Korea, MiG-17 flew in Vietnam. As did the MiG-19 and
MiG-21. The -17 was the last of the gunships with twin 23mm and a
single 37mm gun.

and never, ever engaged you at supersonic speeds from 5 miles
away..

Correct, the reason being the -17 wasn't a supersonic fighter. AFAIK
it'd only go Mach in a dive.

To their credit the Pentagon listened, equipping Sabres with
50 caliber guns to even the odds

The F-86 Sabre had 6 .50cal Brownings from the get-go and flew in
Korea. The F-100 Super Sabre had 4 20mm revolver cannon and was the
last of the USAF's gunships IIRC. Ditto for the USN's F-8 Crusader.
When the F-4 Phantom became the front line fighter for the Air Force &
Navy it was a missile-only bird until the pilots bitched enough that
gun pods were hung on the centerline. The F-4E was the first Phantom
variant with an internal 20mm. Now I read the gun debate is going on
yet again with the F-35 JSF. Maybe the designers should read up on
their history?

Whew. Sorry about the thread creep, got carried away with my history..