F-16 "training rounds"? From this Wikipedia article


  A fighter pilot based at Andrews Air Force Base, Billy Hutchison, claims that while in the air he spotted Flight 93 on his scope and planned to first fire his training rounds into the engine and cockpit, and then ram the airplane with his own jet.[135][136]


One of the references refer to these as "practice rounds".

What are practice rounds? Are these a special type of ammunition with inferior performance to standard ammunition for the M61?

From the M61 article I found that these rounds appear to exist: "PGU-27 AB training rounds"

Are these the correct rounds the plane was supposedly loaded with?

The article seems to claim they are both cheaper and more effective than standard rounds, but maybe I'm reading it wrong.
Less effective.  20mm projectiles are normally explosive.  Training rounds are non explosive, basically really big bullets, and are coloured blue.